The Super Tiger GS-45 is a good runner and lately as cheap as they come. The TT would probably be darn near a drop in. They are good engines as well. There are several good engines not on your list. Irvine, Enya,MVVS and Webra are all good engines as well. If performance is paramount I would go with MVVS. If durability is paramount I would choose Irvine or Enya. If cost is the deciding factor I would coose ST or TT. Good luck with whichever engine you end up with.

Mark Shuman