What year/model 350ci can replace my 94 305 Z71

[Barrett]

I have a 94 Sierra 1500 SLT Z-71 with a tired 305 engine and my son and I are looking to replace it with a 350 (which I should have ordered it with initially!).

What years and models will enable a swap without changing wiring, fuel system etc. Seeking a clean proper replacement. Will a change of the ECM be required?

305ci with auto, 4x4, a/c

Thanks!

Barrett