The modifications I've made so far: I had previously sealed the rear plate, the exhaust and the cylinder head. I had also completely checked out the fuel supply system to insure that there are no leaks, crimps, bends, or anything that would inhibit fuel flow. Using suggestions found in this thread, I removed the carburetor body from the engine, removed the fuel nipple from the carb body and observed the partially blocked hole. I first enlarged the fuel nipple, then reinserted the fuel nipple and enlarged the hole in the carb with a drill bit through the fuel nipple so that the threads of the carb body are not damaged. This is a blind operation because you can't see what you're doing, but by going slow and checking several times by removing the fuel nipple and taking a look, it takes only a few minutes. I gave the carb a bath in alcohol to remove any filings from the drilling operation. The only issue I had was when reinstalling the fuel nipple to get the engine back together, I twisted the fuel nipple off leaving the threaded base stuck in the carb body. I should have anticipated doing this because the enlargement of the fuel nipple weakens the walls of the threaded base. I was able to back out the threaded base and install a new nipple in the carb body. I haven't enlarged the new nipple. I sealed the carb body when I reinstalled it on the engine. I don't think I'll need to shorten my spray bar. I have a gap between the end of the LS needle and bar when at full throttle - the gap is small but visible. I will run the engine tonight and report results soon. (I have not enlarged the exhaust nipple for increased back pressure nor have I tried a baffle yet - these steps will follow if it still quits in the air.)