These are the local SE guys that are always out at the track to support us grassroots racers, everything you should need:
http://www.discoveryparts.com/cgi-bi...?product=hhard
Ron will prob. be the guy who answers. If you are a NASA member, you get a 10% discount.
I have my shoulder harnesses on my roll bar, everything else is anchored with a backplate. Prob. wouldn't hurt to have the backing plates welded in. May be overkill, but you can never be too safe.