Man..!
You did a great job of getting down to the bare minimums.
I'll bet it's good for 105 mph. If you were to do the "Toad Mods" on the AME, you have a plane that will take full advantage of that, too.
Toad hangs out at rcg...but he's got his old RCU posts floating around in CyberSpace. I've found that Google searches can pan out with the right key words.
Basically, the mod improves transfer flow after you notch the skirt of the piston and grind a corresponding notch in the crank's counterweight. At BDC [and a little bit before BDC] the transfer port has an unobstructed path after you do the mod.
I like the color of the leading edge on the red plane....is that paint...?
Your Magnum turned out very slick and I'll bet it looks great while it's zooming around and passing the bigger planes....