I'll agree with most all of this except #17... a junk yard motor will be more reliable than rebuilding your 302. I've noticed a long trend with the op being dead set against rebuilding engines. I've been down both roads. You never ever ever ever know what you are getting with a jy motor. EVER. While most noobs may not be familiar with foxes, they may be familiar with overhauls, and I've said it a hundred times, a monkey could learn to do it. When you rebuild a short block, you know it's tight, wont burn oil, and won't let go when you floor it. I've been doing this literally since 1986. My first car had five junkyard engines in it before I said screw it and built a good one. NOW, that being said, I will agree that if you are making changes the best thing to do with the stock top end is to throw it all away and go with explorer or better parts. Performance wise, the factory mustang top end stuff is really poor. The bottom end, however, is every bit as good as explorer.
This is pretty damned good but I'd like to add one portion that SHOULD make some others here nod in agreement:
Even if it's your first rebuild, unless something goes horrible wrong then the final motor is probably going to be as good as or better than a pro-rebuild for one simple reason. You're checking everything half a dozen times because it's your first rebuild and are probably going overboard on most fine details. Everything is torqued to spec (using actual torque wrenches and everything).
At least that's what it was like for me. I didn't know enough to it wrong and followed my rebuild instructions meticulously. I wore my buddies phone out (you remember those, they were cordless and worked pretty well over short distances with the antennae pulled to it's 3 foot maxi) calling him up when I wasn't sure about something.
I think that the only people that would balk on this specific portion of the topic are the ones that just cannot use tools. These individuals would be best off installing an uninspected JY motor. I've also tossed a motor or two into a car re quick because it had to be moved. I STILL don't know what's in my 89.