Funny in the 850 Thread link Tuner made the same suggestion about plugging 2 & 4 unless the fuel level is lower, the 1 &3. Obvious his posts have influenced me!
Mark mentions in this post that he'll sometimes use the very bottom e-hole in deep wells for alky and oxygenated fuels. holley billet metering block and emulsion jet question
Doesn't seem like your situation, although if you had three bleeds restricted to .020 you could experiment with that.
McMaster Carr stocks 3/16 set screws and shipping is based on actual shipping cost.