Pull a plug, what did it look like? Do you have a regulator with a gauge on your new set up?? whats the fule pressure set at?

Its a Mustang with a looks to me a non-HO 302. Has a 600 vac secondary on it.

Fix the exhaust leaks and do a good tune up with decent parts (wires) and get rid of those 3mm skinny wires. Once you get a good foundation then tune it.

Edit: I'm not a fan of a vac secdary carb.