Jack,
Another thing occurred to me today while driving home, listining to the Explorer ping on the overpriced crap they call gasoline.
How much compression does your 302 have? And does it have a relatively mild cam?
You may need to run a higher octane gas than the junk that comes from the pumps these days. A radical cam with a lot of overlap will bleed off some cylinder pressure and lessen the octane requirement, but only to a point.
After my cam break-in, I ran my motor for a total of a couple hours to heat cycle everything several times, and check for leaks.
I ran out of gas, so I tried running it on 93 octane pump gas.
It heated up to 200 degrees in about 5 minutes on that junk, and this was under no load at 2000 rpm.
I got another jug of 110 octane and she would run all day at 180 deg.
Try some Cam-2 or other high octane race gas and see if it makes a difference. You may even be able to mix it 50% with 93 octane.
Also, if you need to do any major work, I have a large shop with a lift. You're welcome to bring it down and I'll help any way I can to get you on the road. (But only if I get a ride)
Later,