Before I comment, I can not seem to figure what motor you want, a 6 or a V8. That's first. I also do not see why a person who says they are over their head and want to go low budget, is looking at all those funky mismatch motors and trannys. Also would like to know what the difference is between a K10 diff and a c10 diff.
Sorry about the repost, was still typing.

Replacing the motor with the same era motor is by far the easiest. It's a bolt in! I have found if a person has patients and lives in a populated area and uses craigslist, you can find a running motor, still in the vehicle for $200-$500. Sometimes, if it is the right vehicle, I have purchased the whole vehicle and sold parts, got the motor free and made money. This is an especially way if the seller has no title. Hard to sell for him. If a seller says they just rebuilt motor, I walk away. There are plenty of sixes with plenty of miles left. Examine, run it, drive it, compression check, buy it. Find out what the newest, best internals, most reliable motor that will bolt in from Stovebolters here, they know.


Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn