mounting it might be tricky. I think the rear mount could only go to the seat tube, it's a horizontal boss but that 4 stroke plate will get you closer. some vendors on ebay have more pics, maybe you can see one of the bottom if you look for pocket bike engine on amazon or ebay. many listings for these.
These have a higher working RPM than the HT engines and they're auto clutched and wider than your basic HT engine, best used on a rear rack mount. The transmission that some optionally come with is only 3.2:1 ratio and the stock chain size is the odd 8H 8 mm pitch, very narrow chain. Like on a Honda OHC motorcycle's cam chain. Final drive sprockets are harder to find different sizes for, I've only seen 11 tooth and 44 as the rear sprocket. so it's going to not rev up much on a 26" wheel bike. These engines need to spin, they don't lug down well and the clutch engages at about 5K rpm.
The plastic engine shroud and pull starter are a bit weak and often crack. But you do have forced air cooling, it's a plus for an engine that tends to run fast and hot.