Not questioning your measurements, but at 3.15 pounds, that TT 1.20 is way heavy! For comparison, the OS 1.20 AX, with muffler, weighs 823g (1.81 pounds).

I guess you could use either one of your engines, but I would surely stick with the larger airplane. If the smaller one is designed for a normal 1.20 it might have a hard time carrying that super heavy TT.