IIRC the front frame is basically the same as yours is still a 1st gen Wbody. My 96 Monte is a 1.5 gen as i have struts in the rear vs the leaf spring. you have plenty of options. if you are lucky i would grab everything from a 98,99 monte Z34 and then do a top swap.
engine mounts for the 3800 will work fine for the current cradle.
my AC lines worked fine from my DOHC to the L36
I needed to change: power steering lines, fuel lines, throttle cable.
If you run a 4t65HD you will need to make a hybrid passenger side axle as the HD pass axle is too long. You will need the outer from a 98/99 z34 and the inner from the HD. also they have to be OEM axles as aftermarket have diff splines and will not join up.
You want the 98-99 Z34/LTZ harness as it connects everything from the engine and has the same C100 connector to go thru the fire wall. I have wire diagrams saved if you need them for many different year w body C100 connectors so that you can adapt the harness to your connector.
Also being you are OBDI you will most likely need to update your instrument cluster or possible other systems in the car to be compatible.
If topswaping, you will want headers. I chose speed daddys and some go with true pacesetters. both require fire wall modification I had to cut about a 8-10" turtle sized notch out of my fire wall to make room for the down pipe. if you plan to do any mods at all to the engine plan for headers while the engine is out.
I say go for it! I enjoy mine being swapped. granted mine was OBD2 and i had a complete drop in from a 98Z34 to go in my 96Z34. I knew it would all fit without problem. the early W bodys were much lighter then the later 2nd gen's possibly one reason I am able to put down a 14.9 with an NA 3800. only real mods are full exhaust, HV3, and tuning.
