Here is a pic of a Blackhead .19. Don't think I've ever run it...just oil it up once in awhile.
I have another in my shop that has been run. I bought it used and put an OS needle in it. The original needle assembly was missing.
As you say, not all Red Heads were bad fits. I have two of the older ones that both have good fits. I believe GMA also said that one downfall of the Red Heads was using fuel with insufficient oil content - Testors 39 was a prime example. IMHO when you run the pee-waddle out of a sport engine, you shouldn't expect it to last.

George