I bought this NOS Diamondback steel cruiser frame for $31 on ebay:
It has guides for rear v-brakes and 7-speed derailleur.
What a deal!
Hopefully, my 6hp Robin/Subaru OHC engine fits w/little problems. I'm shooting for 29" ROCKSHOX fork, 29" Schwalbe Big Apple front tire, 26" Big Apple rear, disc brakes, 7-speed derailleur and shift kit. If the cassette fails, then maybe a NuVinci hub.