I did some more research and found that the Harbor Freight pump didn't have a clutch, but a shaft bolted to the flywheel. So, if this engine is similar, you'd need a clutch with two holes and some hardware. The Dax clutch is for a 4 stroke and wouldn't work.
Here's a thread on the Harbor Freight 2 stroker pump:
Maybe you could bolt a drive roller on the shaft for a cheap alternative and save a few bucks. I don't know how long that bolt-on shaft is.
Good deal? I don't know. You can buy a 99cc Predator on sale for $99.00. But if you need a compact 2 stroker it might be or spend about $149.00 plus shipping on a 3hp 2 stroker from Dax.