I found a 1996 series 2 3800 in a regal GS. would I be able to take part off of it and put it on my 02 L36. I am thinking that I would port and polish the intake and the heads. then when I get a chance swap the heads and intake to get the better flow. then do the same to the original heads and intake and then while I have them off do the rockers and the pushrods and the springs. If I can get the motor and tranny for 650 should i jump on it

I heard of some minor change on the heads having to do with springs. Also the trans is a 4t60 not the 4t65 you have in the bonneville. Other than that the rest should be fine.

check part numbers comparison just to make sure.

I think you should be alright. You might want to check the PCV location to see if there is a MAP sensor on the '96, as I know the '95 L36 did not have a MAP. Not sure about the heads being different.... I would imagine they would still bolt right up. If you're planning on using internals, I believe the pistons should also be the same, though there may be some anomalies between the '95 engine and later years.

the heads are different PN'* and different casting numbers

there was a update in 98 for the newer heads, that are less prone to cracking

The manifolds still have the provision for the MAP...the 95'* have a blockoff plate that can be removed very easily. How many miles are on this older engine? It would be a wise decision that once the engine is verified good to use, to replace all the gaskets, any sensors that would normally be hidden, and a change of lifters...the 96 engine I bet is getting a bit tired, all of the above mentioned will help it greatly.

the motor has 81k on it

If all your really interested in is the heads/lim I would look for something cheaper.
I got heads for $50 and by some fluke I got a UIM/LIM off ebay for $0.99+ shipping.
If you look hard enough I'm sure you can get heads for under $100 and a LIM for under $40.
When porting the heads don't go wild just gasket match and smooth out casting flaws. Same with the LIM.
Your n/a so your goal is to increase air velocity not just flow possible (cfm).
You'll need a Standard Abrasives kit, die grinder and air compressor.
Have the heads milled 0.020". That will bump the compression up a bit and allow you to use stock sized pushrods without overloading the lifters.
You really don't have to upgrade your pushrods for strength.
Make sure to lap the valves in good or even better have a 5 angle valve job done.
Port your exhaust manifolds while your at it.
And get some Comp Cams 105# springs and LSx style retainers or some LS6 Springs and comp LSx style retainers if you plan on going past a 1.8:1 rocker ratio.