Well it's been a long road, but well worth it. This old girl is finally running great after 4 weeks of testing, tuning, and waiting to receive jets a few times over. I've got some jetting numbers to share to feed the hungry baby birds out there who seek to run a bleed type needle jet. Keep in mind, these numbers work for MY bike in MY conditions. Perhaps it will get you in the ballpark and save you some cash.
1972 Honda CB350 twin
Generic 12" shorty mufflers, freshly repacked,[u] with additional baffle inserted before muffler</u> for a bit of backpressure and less raspy pop
NEW Mikuni VM30's and K&N pod filters
Fresh points at proper gap, condenser, plugs, valves checked, correct timing, clean and smooth timing advancer, good compression
87 octane fuel w/10% ethanol
Typical hot summer, sea level.
Main Jet:Large Hex 200
Emulsion tube/Needle jet: BLEED TYPE
176 series P-8
Needle: 5F3, lowest (richest) clip setting
Air Jet: 0.5
Air Screw: 2.0 turns out
So far I've got a few hours of spirited riding on this combo and it feels great from idle to redline at all throttle positions. Plug has a slight cardboard color so far and I'll keep an eye on it. The bike can idle for an extended period and still have a clean off-idle response. I'll eventually try an even richer needle to get the clip settings closer to the middle, but let's enjoy it for now. Hope this helps.