Before I build one, I wanted to get a head count. I would be going to Vintage Torque Fest (show), Back To The '50's (show), Meltdown Drags, Fallout Drags, and HAMB Drags. Hopefully more, "near" Iowa. I have wants to build the dragster, but probably more of a budget to build a rail.
There was two of us at the meltdown this year. Neither of us are HAMB legal. There was also a couple ex-HAMB dragsters sporting V8 engines. I think only one SDRA (Tulsa) car was at the HAMB drags. There's pockets of HAMB-like dragsters in SO. Cal, the Pacific Northwest, Australia, Tulsa area, one in Florida, one in Wisconsin and one in Minnesota. That's all I know of. It appears there isn't a movement to build these cars. But I can say my experience is it was fun and relatively inexpensive to build. Now that I have my car and my procedure pretty well under control I can run the car with no help and have a great time doing it.
The HA/GR (Hokey Ass Gas Rail) is an "official" HAMB class. The rules can be found here; https://www.jalopyjournal.com/forum/threads/ha-gr-rules.299965/ The C/GD (Cool Gas Dragster) is an unofficial HAMB class that was originally created/thought up for the Eagle Field. The rules can be found in the first post of the thread here; https://www.jalopyjournal.com/forum/threads/eagle-field-a-gas-dragster-class-build.430809/