The LT1 was THE optional 350 in the 94-96 9C1 a 4.3l V8 was standard. It is not compatible with the 93 Caprice 350. To oversimplify there are a lot of changes to cooling and engine management but the crankshaft/rods/pistons are all interchangable, so it is kind of like a lot and a little is changed.
I am going to go out on a limb and take a guess as to why you are asking, if you found a 93 Caprice 350 to try and put in your 94 car forget it, if you have the 4.3l in your car I would keep it over the 93 350 they make about the same HP, and if you are looking for a replacement for a 94 LT1 then the 93 engine is a huge step backwards, like 200hp instead of 260hp.