How much prop does it turn? The current crop of pattern planes really need at least a 19" to work properly. If it turns say a 19-11 or 12, at around 7- 7.5k, it would work okay even if the plane weighed 12#. If it turns a 20-21" prop, even better. It probably will need a pipe to get the mid range torque. I don't have any experience with ST so don't know capability first hand..... maybe someone else does and can chime in?

As I've stated before in this thread the GT33 turns the 20.5x10.5 APC at 7100 and the 20x10.5 at 7400, burning avgas. On premium autogas it will turn +300-400 rpm, same props. These are all very sporty numbers and produce incredible performance on an11# pattern plane.

Good of luck with it.