70 Shortbox Chevy 2wd considering a GM 3800?

[blazerboy_4life]

Hi there this is my first thread. been coming to the site for years though. As the title says I have a 70' Fleetside Short Box. I would love to put a motor in this truck that would make it do a wheelie but with fuel prices steadily rising im leaning more on the practical side of things. I found a GM 3.8 V6 out of a 96 Pontiac van for $150. It has 150,000 miles and runs great. Comes complete with computer and all (Craigslist Find). Also found a complete Super Charger for this motor for $100 (Also a craigslist find) Has anybody ever done this motor swap in an old pickup like this? If So was it easy? What needs to be done with remapping the computer? Im going to pair it up with a Post 87' 700R4 cause i heard the valve body was stronger then? Im hoping for north of 20mpg. Is this even plausible? Also side note is it difficult to switch over to power brakes from all drums. Thanks for all the advice everyone.

PS any mod suggestions or your favorite mods for this Gen body style are welcome to.