I am in the process of building a modified Brodak Super Fly, "just because". I shortened the wingspan by 5 inches, added fixed flaps with a 2" root chord, and replaced the wing tips with solid block tips. I also shortened the nose 1/2" and only used a single 1/2" thick cheek cowl. I changed the stab and elevator for cosmetics, but used the original wood. There are also a few structural mod's, like a carbon fiber nose doubler and a beefed up center rib and bellcrank mounting. I also used a 3" bellcrank. I don't know if it will be any faster, but to me it looks more "right". Time will tell.