[cdowns]

WELCOME TO THE BOARD

#1 for a GMC style front it's really better to change the whole front clip

#2yes beds are interchangable and just bolt on

#3 yes you can make power with a 6cyl// but you can make more power cheaper with a 350 as the parts are so plentifull and theres tons of gently used parts to save even more money

#4 READ READ READ tons of tech articles from every magazine ever printed

$5 yor dad its pretty darn close with the MPG estimates. stock 2wd with 350 is not unusual for it to b in the 12-14range but it can b increased more easily than the 4wd trucks
overdrive trannys are thge single biggest gain in MPG they have the benefit of very low highwayRPM plus around town gears are excellent on acceleration. max MPG can b achevied with fuel injection if you wish to have computer controler
a 2wd carb truck can get in the 16-19mpg range pretty easily// i've heard of fuellie trucks getting over 20mpg but have no experience with them

all the mpg ratings are of course HIGHWAY miles around town is a different story

GOOD LUCK WITH YOUR PROJECT and have fun and listen to you dad // you'll find out 25years from now that he really aint that dumb