I've got one of those old streetmasters. It's surprisingly heavy with all the extra aluminum in it. I've been wondering forever what it would do if someone milled the plenum open and cut the runner dividers back to a knife edge about an inch past the plenum just to see what it could do. It has nicely swept runners and no bolt pinch at the ports. Modified like that with the addition of a 1 inch open spacer I suspect it would be like a downsized version of an Offy Port-O-Sonic or a Weiand Xcelllerator. It would almost certainly have to be better than the Edelbrock TM5 or Torker 340 intakes that were available at the same time.