Re: been a while, building up a new bike.
As far as a frame goes, just about any steel cruiser frame should work. If you're looking for something new and inexpensive, the Huffy Cranbrook can be had at Walmart for usually under $100. In my experience, its been a great, solid steel frame. You may want to consider upgrading the wheels, but if you already have Worksman rims, that should not be an issue. If you're looking for something more old school, maybe American made, I might suggest perusing craigslist for a Schwinn cruiser frame. The Schwinn cruiser frames with the skinny tubing are almost definitely American made as far as I know. The 79cc Predator is a fine choice. The 212 is not really necessary. The only jackshaft that is cheaper than agk's is the ProMod jackshaft, and its only about $15 cheaper, so that won't save you a ton of money. Building a non-kit 4 stroke is not the cheapest way to go as far as initial costs, but imo, worth it in the long run as it will save you money later on. With proper maintenance, the only things you should need to replace are the tires (they all wear out eventually) chains (they stretch and get worn) and the sprockets (as the chain wears, so do the sprockets over time).