If the steel heads don't need guides, and the valves are good to use, having the steel heads cleaned, lap the valves and install the springs needed for your cam is the way to go. If you can do all this yourself all the better, but to find a good set of steel heads is the key. If you have a bare set of heads, that need vales and than need guides, adds up quickly. I had $500 in a repairing of set steel heads I had on car. Broke the motor, bent 7 valves. Had a machine shop plain the heads to clean them up and install 2 guides. My dad did all the other work and installed new valve springs.