Hi bentwing, I have used several Saito engines on a lot of different types of aircraft including warbirds. First , the Saito engine is an outstanding choice, power , reliable , and a 3 yr warranty.. I have used the .56, .72, .91, 1.20, 1.50, 1.80... If you are using a .60 model, the Saito .91 or 1.00 will be outstanding unless you are wanting your warbird to hover in place? the power to weight ratio should say .91 but the 1.00 has a little extra punch and wieghs less than a OS .91fs .. I think the wise choice would be the 1.00..............Bud