Easy shouldnt be in your vocabulary when discussing a V8 swap. What are you going for? Just power, reliability? Not trying to sound like a dick but Im just wrapping mine up so it is all fresh in my mind.
Edit: like Morris 4x4 said, probably a carbed 350. though that is why I did my V8 swap, to get fuel injection.
Carbed would be the cheapest and easiest but I think if youre gonna do it, do it right. My buddy just swapped a 5.7 Vortec from an Escalade into his 88 Blazer to replace the TBI 350 and he is impressed with the additional power.
I went for a 1996 Grand Cherokee with the 318 V8 in it. That way I have all of the emissions crap, engine, wiring harness, and some other goodies I wanted for my project, all for less than a grand. Keep in mind, in order for this to fly as being legal, the engine needs to come out of the same year Jeep, or newer. That means you need an engine out of a 1991 vehicle, or out of a newer vehicle. And for the sake of not breaking ANY Federal laws, you need all of the emissions equipment out of that vehicle for that engine.
saving my own hind quarters, don't want to look like the bad guy