should still be more than enough power. 1/10 scale nitro stadium trucks originally used .12's and later with RTR's .15's and those boogied, the HPI Nitro RS4 MT had a .15 and that thing got down! (it was also 4wd) even with a little larger (longer) size of a short course truck it should still be more than enough. short course trucks don't weigh that much more than an old stadium truck but the wheels/tires are less weight cause they're narrower. so rotating mass is, at least in theory, lower making it easier to push.
if you're overly concerned about power maybe look into the HPI 3.0 engine. i believe it's a .18. i have one of those in an HPI Nitro RS4 2 touring car. that car originally had a Nitro Star .15 and the 3.0 is noticeably more powerful. ...goes through fuel noticeably quicker to...(drains the tank about 2 min faster)