Aluminum heads are great if your budget can afford it. Your 73 heads aren't worth too much (do you have a casting number of your heads?) They're most likely one of the first emission heads and are low compression. Probably have 1.72" intake and 1.50" exhaust valves. You'll spend alot of money rebuilding them and they'll choke down your airflow. If budget conscious, buy a pair of better iron heads. They perform just about as well as aluminum. Aluminum will dissipate heat quicker and are easier to repair if something happens to them. Some say that in higher compression applications, they tend to alleviate detonation problems. I personally use good casting iron heads. Some of the cheaper but good ones are the 040 castings which were 327 truck heads. Summit also carries their own brand iron heads for around $600-650/pair assembled.
