Can use some Thermostat and Rad Cap advice

some suggestions to the OP:
use a high flow thermostat if you can find one. I am assuming that you have an intake with the larger thermostat. Given your cam and stuff I'd go with a 160 degree unit. Mr. Gasket #4366 (they also have 180 units). This is the same type of thermostat that Mopar Performance used to sell (Robertshaw style?).

I agree with Rusty regarding pressure caps. If you have no info on the history of your radiator, like when and who it might have been recored by, then too much pressure is pushing your luck. I've been using 7 lb. caps since the early 1980s on my 70 Darts with no issues. Since you have a recovery tank, you'll know if this is too low.