1st question - only diff is the big truck might have had a governor under the carb, easy to pull off
2nd - very little required to put it in a 58, as the 58 could have had a V8 optionally, and just requires the repro stock front mounts for the 58 - might be side mounted in the 65, but those could be used too w/ the adapter cross member
3rd - the truck 327 = 250horse, 350torque at 2800rpm, usually w/ 4 barrel carb I think
finally, if you need even more than double the 235's hp, look at cams and maybe find bigger valve heads, but the stock 327 will spin your tires more than a sane person could afford anyway
Bill
