Re: Suggestions on engine to get?
No. The Chinese are the only ones currently marketing engines designed for bicycle frames.
There are several styles including rack mount and friction drives if you don't like the chinese in-frame kits.
Any aftermarket engine will take some work to fit on bicycle. The "Chinadoll" in-frame engine is by far the most popular, but Dax, Staton and several others make different style kits.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.