Looking at this engine will it work?

I have a chance to pick up a Lifan 97cc from a doodlebug. I have checked out the Lifans and they seem to be about the same as the predators. This guy is selling this engine with the clutch that came with for the doodlebug.
My question is, is this pretty much the same as what is being used for motorized bikes. I am about to start a build on a early 1940's schwinn DX 24" and want to try the four stroke rout.
I already have done the two stroke so a newbie on the 4 stroke. He wants 90. for engine and clutch shipped is this a good deal? I hope this is the right area to post this question.
Thanks for all and any info on this.

I also read that these 97cc are 2.5 hp I am wondering how that compares to the predators. Anybody? Bueller, Bueller?....
It looks like the engine is possibly a flat head? I found another post on here where some dude did the double doodle engine on a bike that looked tight. I guess I will try to pin him down as well with some questions. The engine may be gone soon so I am just checking options.
So,... I am just trying to figure out if anyone has used them what kind of performance they have and is the clutch that comes with them doable for a direct to chain (Rear Sprocket or if a jack shaft is needed) drive?