The Mach I is a thing of beauty in flight with retracts! The nose was especially designed with a flat area on the bottom to make the nose gear installation easy. Back in the day Rom-Air were the retracts to have but they are no longer are in business. In my opinion the Spring Air retracts are one of the best. I would think you should be able to build it with tri gear retracts and be less than 7 1/4 lbs.

Norm Page would be proud!

If you plan to fly in SPA events they do not allow retracts to be retracted in flight and most use an OS 91 4Ss for power. I noticed that you are in CA so I do not think SPA has reached that far yet. I’m not a fan of 4S engines and I fly with my gear retracted so that gives me a free pass on SPA events.