It should most definitely fly, my Big lift weighs 14,5 lbs (6,5 kilo) and has no issues towing about 8 lbs gliders. Perhaps you need to give a bit attention to the cooling air (baffling, and it needs to be effective, not just a "bulkhead" around the engine), because the engine definitely needs to work a bit.

It would not be my first pick, because that combo is not "unconditional".
If I had to do some estimates, that husky will absorb around 1, maybe 1,5 hp in level flight, and from my experience the open and exposed twin is capable of over 2,2 WOT up to about 1 minute, and at least 1,5 sustained indefinitely. Properly baffled engines cool better than open and exposed ones, so done properly, there are no issues whatsoever, but that is the condition: "done properly".

Mind you, I am careful in my estimations, probably the limits of sustained operation are wider, but I would hate to see somebody wreck an engine "Because Brutus said it could be done".

It would be light on power compared to the engine recommendations (the ST2500 on meth has more power than the OS/ASP twin on gasoline) but I am pretty confident it will have enough power for safe flight. It will be a bit sedate maybe. I think, I would like it for those endless no-wind summer evenings.