A better combination is a Saito .91 4C... two oz. more than the OS .70 and goes like a scalded ape with an 11x12 APC prop.

BTW I originally had an OS .70 on mine. It flew quite well with a 12x7 prop. It also balanced perfectly with that engine - no extra weight was required. I didn't even have to futz with the placement of the receiver or battery pack... I simply ziptied them to a former on the CG. Battery pack in front, receiver behind.

When I swapped in the bigger Saito I had to shift the battery - I ziptied it to the rear of the receiver and it balanced fine.

OTOH your Irvine .53 will pull it just fine. Be prepared to add a couple of ounces to the nose in order to balance it. Stick with 12" diameter props for a while - the plane responds quite well to the extra propblast over the wing at low speeds. Your landings will be a lot smoother.