Intake reversion is what causes your engine to drown itself in it's own fuel,

Agreed. Other motors show that this is not typical of the intake length, cam, and header I'm using. It's the rest of the exhaust system that's wrong -- it defeats the header in the problem range.

but you should be able to jet around that problem with ease. F9 or F16 emulsion tubes for hot B20's, F15 for stock B20's.

Should, but can't. Tried F15, F16, F46, F2 and F7 tubes... makes very little difference. Moves the start and end points of the fat area up or down the rev range a bit, but does little else.

What size chokes have you got in it?

42mm, and no, I'm not going smaller, thanks.

Stock ignition with points can get any NA B20 engine to 7000+ rpm.

Yes, but I don't have stock ignition and points. I have an aftermarket system that's worse. It won't support even the stock plug gap -- the directions actually say that, as I have now discovered.

Did I ever send you a list of DCOE jettings that I have used for various engines?

You posted them on this forum and I saved them from there. I tried to e-mail you a thank you note, but the address I had for you bounced.