Sources: Large Port Commando Heads

The large port Commandos are very close to a W5 head without the raised intake port. RHS, Edelbrocks and such are not going to come close to the potential of this head.

Back to the OP's original question, you should check the big MP dealers, Jegs, Summit and such. Or maybe you can talk a local dealer into giving you a deal on some parts if you are going to spend x amount of dollars with them.

You may also be able to find a used set on eBay or Racing Junk, used W5's pop up from time to time as well and that's actually a better head than the LP Commandos.