Will a 92 Chevy Capri 305 fit in a 95 Silverado 12 ton?

Yes it will fit right in there. A small block Chevy is a small block Chevy.

The only thing that is different is the fuel system. All small block Chevy engines are the same it does not matter. Chevy did not redesign the engine blocks until late 2000.

But in your case the 2 ingines are the same. Put it in there.