Engine upgrade

I am interested in upgrading from my 4.3 to either a 305 or 350. Will the 5 spd manual transmission be able to handle the power from either one of these engines. What other changes would I have to do. Any help would be much appreciated.

I was planning on doing the same thing till I found itd be much easier and cheaper to just put in a brand new 4.3l. If you go through with it the tranny should beable 2 handle the power but you will have to get a new fan shroud because the one for a v6 is smaller. If your truck is EFI you'll have to be sure the new engine is compatible with that and see if the cpu needs reprogrammed for more fuel for the bigger engine. You might need to look into a bigger air intake and filter but other than they everything else should go together just fine. Also i'm not sure, but you might want to check into getting a bigger radiator otherwise the engine may run hot.

What truck are you doing this swap in? This will greatly effect your questions.

The truck is a 91' 1500 4x2,w/5speed transmission.
I was thinking of going with another EFI system or going straight carburator, with the self contained distributor.