James:

I just did the math and now I see that your airplane is smaller than the usual 120 size.

Perhaps the 160 and the ST 2300 would be too much for that airframe. The 108 would be a great choice. It is an reliable as a stone, which is why it has been in the OS line-up for so long. If you want to look for a little more power, the GMS 120 is a big step up powerwise from the TT120 and weighs about the same.

The more I think about it, the more I think the 108 would be the engine for you. Use a flat pitch prop like a 17x6 or a three blade 15x8 Graupner and you won't overstress the airframe.

Jim