There's a guy in the 94/95 forum with a 331 running 185cc patriot heads, x cam, gt40 tubular, 24 lb injectors, STOCK maf, 70mm tb, that pulled 321hp and 374 ft/lbs with 12.7 a/f ratio. So on a combo that isn't as good, he made 15 more hp and 23 ft/lbs more torque.....there's something wrong with the tune or something,
The torque is pretty good but your 331 has a bad case of asthma and the primary cause is the Cobra intake. You have a 210cfm intake which is choking off your 260cfm heads. You could go for a Holley Systemax II instead. It'll definitely add more HP at the top end with minimal TQ loss lower down. Add a 75mm TB, 80mm MAF, retune the chip, and you should be golden.
What's the general rule of thumb I know I'm going to do a 331 stop block and I have a few intakes that I would like to run and a few heads that I'm thinking about. Do you pick the heads first and then match the cam?
Cam last. Pick your heads, displacement, intake and then figure out how you are going to drive the combo. Race car? Daily cruiser? Cam selection will change. Ideally you wait for the end because if you have your heart set on a 331 and then something changes, that would affect your cam selection. Leave it to the end and then.