Thanks for the replies. Looks like the LS Pro is the winner by a scant 1/8 inch. There's actually a tad more, maybe 1/2 overall, which will work. At least I know there's something out there. I thought my ZDZ-50NG was going to fit, but it missed by 1/2 inch with the plug cap on (this is for a 1/4 scale BirdDog). I'd rather not have to cut the cowl, even underneath, but I really want to use this engine, although the thought of the twin is attractive, since the cowl has those "nostril" intake holes in the front, you'd be able to see the cylinders. Lots of time to think it over.