4.3 will bolt in place of a sbc , same bellhousing , 3800 is not. no 4.3 I am aware of can make power or survive it like a 3800 can
basically a 4.3 is to a series 2 or 3 3800 what a 5.7 vortec is to an LS engine like a ls1 or 6.0 - good but inferior as far as durability at least on stock rotating assembly....
the series 2 engine is on wards 10 best engines of all time , the series 2 and the LS1 were developed by gm powertrain around the same timeframe (mid 90's) , simple single cam , cross bolted mains/6 bolt mains ,etc...nothing exotic good explanation here: http://www.thrashercharged.com/tech_htm/engine_tear.shtm
I have a complete engine/trans dropout package with pacesetter headers , Wizair intake , ZZP modular pulley system ( quick change) with 3.4 pulley , 1.9 ratio modified stock rockers by zzp , tuned pcm , harness complete package out of a 2 door 97 gtp , car ran 13.3 @103 last time at track on dr's for previous owner - entire package for $700 and you can hear it run first. make it $900 and you can have the entire car with 4 torque star factory wheels which are the lightest offered on a w body at 16 pounds each, this would also give you the 2 speed gtp fuel pump and cannister , and it has heads up display , car is rotten and hit in the pass 1/4.
prices are firm as the shell is worth 300 in scrap after pulling the wheels , hud , drivetrain , as well as countless body , trim and mechanical parts that are good on the car
top swaps are popular and I have sold many of them online , basically you would buy everything above the block deck off a supercharged car , heads , lower intake , supercharger , throttle body , fuel rails , sc coils ( more powerful than na) crank hub and idlers to run 2nd belt to drive sc but top swaps sell for around $400 then you need to buy head gaskets , intake gaskets ,supercharger gaskets , and replace all the torque to yield bolts on the heads - people dont realize this adds up to more than simply buying a dropout package ! not to mention the SC pistons are coated to resist damage from detonation ( to a point) and the ring lands are thinner on non sc engines due to rings being higher on the piston so they are more prone to "chipping"
more money and weaker , I never got it but if someone wants a top swap I will gladly pull apart an engine lol
join over on nepontiac.org plenty several guys on there that have done that swap, if you ask over there I think most will say do the entire engine/harness for similar reasons to what I said.
also the SC cars got the hd version of the 4t65e trans thats in your car , what makes in an hd is the differential is beefier ( hd diff) to swap a non hd to an hd it will need the diff , the diff cover , and the shaft that goes through the diff into the trans.the shaft is slightly different and it would work but I have seen guys go through several diffs not realizing they didnt upgrade the shaft with the diff
also your gt has 329 gears , all the sc cars got 293's most that swap from na to sc stay with 3.29's and many with sc cars swap to 329's , either scenario is going to need the tune adjusted for the gear change or your going to have tranny issues.
someone with hp tuners or dhp powertuner can make the change for the gearing or you can get a pcm ( or send yours in) to zzp or intense and they can match the pcm to your components
th package I offered has the hd trans also and I could pull it all on the rolling front subframe with all suspension , brakes etc... and you roll the whole package right under the car withit jacked up
if your budget is tighter than that or you simply want a bone stock sc engine/trans in your car I have been able to buy whole donor cars for 400-500 several times and would suggest whatever you buy you are able to hear it run first. even if you have to spend 700-800 to find an sc car local to you your going to get half of it back for the carcass when you scrap it and if you join the forum I am suggesting you can probably sell a bunch of other parts off it before scrapping it.
you could surely end up with a sc drivetrain for free or close to it if you follow this advice and the best part is if you blow it up its cheap to find another and they are super easy to mod...
I have been selling off some of my 3800 stuff because I havent had the time to get to it , been working 10+ hours M-F as well as 1/2 days saturdays and a few sundays , if you lived close it would be a different story...
but the bulk of the guys on the local 3800 forum www.nepontiac.org are in mass and RI , plenty of guys close to you with good knowledge.
also if your looking for a donor car 96+ is when the series 2 SC cars ( L67) started appearing , 96 cars got a 4t60 trans and have almost no tuning support due to different pcm so look for 97 or newer donors for an easier swap
guy that bought one of my parts cars just texted me that he got the engine out of it today , 120k SC 3800 complete - he wants $400 for it and he is in Mass , Malden I believe , him and another guy split the price of the car as they both wanted body parts and suspension parts off it and knew they could sell the rest , I delivered it to revere this morning - they work quick lol.
this guy also has a gt that he swapped to sc a couple years ago so he knows the whole drill on what your looking to do.....