Lookin' for 12's

Hello, I'm new to this site, but it looks promising- you guys seem to know your stuff pretty well. Anyway, I have a 73 Duster 340:
340 + .030 10.5-1 KB flat-tops, balanced crank/rot assembly, erson hyd cam (296/306 avd dur, .502" w/ 1.6 roller rockers), TTI step headers+flomaster, 3.55 gear w/ suregrip, 6 pack carb setup, Mallory Hyfire VIAL, but i have stock 73 heads =( 1.88 I 1.60 E
with this combo i can turnout mid 13's on street tires, depending on when i can get some traction. I'm saving my money now to have a nice port and valve job on my heads such. I'm going to have them done to a "stage two" set up.
Am I looking in the right direction? Or should I just buy some pre assembled aluminum heads, like edelbrock or MP?
Any suggestions to help me dip into the 12's would be awsome.
Thanks,
Matt