[tonkabilly]

First off, do you have a pull start on the engine? If so might want to look into a roto starter. Way easier to start the engine. Means an extra battery to charge but less blisters. Second, by the sounds of it, the engine is definitely too rich. Should have a little bit of smoke coming from the pipe. Also, my guess is that you do have an air leak. I know exactly what you are going through. Spent a week trying to get mine to run right when I first got it. Didn't think I had one but after I sealed evrything it got much easier to start and run. As for the diffs, when you put them back together, take your time and shim them really good. If you do it right you shouldn't go through gears with that engine. At least I didn't.
Just some thoughts.