Questions about engine swaps

If one already have a v8 Camaro (lets say an 87, 88, or 89) could I put in a 90 v8 engine in there w/o having to replace a plethora of other items in the car? What about a fourth gen engine? I see that people here love to put LT1's (and upgrade to an LT4), LS1's and possibly even LS6's - how much work is that with a V8? How much change is required?

Probably a dumb question maybe I should scour the forums a little more. Not that I'm going to do any of this but I'd like to get an idea of what is involved.

a 350 L98 from 87' to 92' with drop right in.. They're the same engine
If both cars are 305, and both have the same fuel injection type, they're drop in.. If Ones got a TBI and ones a TPI, ther'l be some fuel system modifications.. Not a big deal

Probably a 1000 threads on LT1 and LS1 swaps.. A lot more work involved.. DO a search for specifics

any small block style engine (not LT1, LS1 or derivitives) will fit as far as the short block. bolt right in. when you get to the ones i just listed is when it gets complicated.