Just finished reading the whole thread. Great build. Would love to see the dyno video and the first fire video as someone has suggested.
The "ladder leaf" suspension you have was all the rage circa early '70's. Nothing wrong with it. Functionally same as a "truck arm" suspension. Your leafs act both as springs and axle locator. It is like a "poor man's" 3 link or 4 bar. No pinion adjustment or height adjustment and not easy to change spring rate. For what you are doing should be just fine.
