Mike,
AFR is the way to go and yes stock is hard to find but they are worth it. Here's some info that should help you out.
Call or e-mail this person, he works at AFR and will be able to get you the right info on what AFR head you need and also point you in the direction of a dealer that "has them in stock".
You should contact Dave Kubert at AFR. Phone (818) 890-0616 ext 111. E-mail address is:
dkubert@airflowresearch.com
Tell him Scott from Classic Chevy 5-Speed referred you over. Hope it helps you out.