Been there, done that.
This $255 GP460 engine, bolted onto a $129 BMP friction drive is the most powerful combination you can ever assemble at this price. With a 1.25" friction roller, this baby screams past 40mph for less than $384. That Happy Time engine will need an SBP shift kit to run with this engine.
At this price range. no other utility-type engine can come close to its performance. Quality engines(non-Chinese) producing 1.6 hp to 2.8 hp cost more and deliver less. Staton's entry-level 1.6hp friction drive kit costs close to $400.
However, there are major problems. Here's my attempt: