I've become pretty familiar with fords, with the amount of them that we sell. The 302 stroked to a 347, and the 351 stroked to a 408, are both viable options. the 351 is taller, as many have noted, and if he has headers already, those will need changed from a 302 deck engine, to a 351 deck engine, as well as intake, and front accessory brackets. so budget depending, that may weight on the decision.
Now. the "347's come apart" wives tail, is just that. this isn't 1976 anymore, where certain aftermarket offerings and combo's are problematic. Anything can be built right, or wrong. at BluePrint, we special design our pistons to combat issues that plagued those early strokers from 20-30 years ago. we wouldn't be building them if we didn't have a way to do it properly.
So if you're considering a BLUEPRINT...then the 347 should be on the table. If you're wanting to build yourself, my same comment of "you'll have more money in machine work and parts than you will in a dyno'd, warrantied, BluePrint" I believe to be true.
Blank canvas....assuming you're not reusing a high dollar set of headers, then the 408 will make more HP and torque for obvious reasons vs a 302 deck. our lead time is probably less on a 408 also.
Feel free to give us a call! if you're doing your own thing, just be sure to REALLY sit down and add up the cost, and labor, etc...I think we're pretty hard to beat.