Booker, I haven't actually started construction yet. Box will be cracked open when the first snows fly. However, I have fitted the engine to the cowl to make sure it works. It's tight, but I think doable. The ASP400 radial is 1/8" smaller(8.66") in diameter than the Evolution 77 (8.78") I'm using. So you're in good shape fitting the engine. The only issue is how much, if any, built-in right thrust we can tolerate without contacting the cowl.