It's the 3 circuit block with the idle feed seperate from the main well. This should allow leaning of the intermediate circuit, without drastically leaning the w.o.t. number.
http://www.blp.com/pdf/pg13.pdf
Here is the offending tube in the main well.

Yep, I run those metering blocks on one of my 4500 dyno carbs. The good news was that I was able to finally tune the three circuit carb so that it would run great for an entire dyno pull. The bad news is that you have to futz around a bit getting everything happy with the thicker metering blocks. (longer bowl screws, longer fuel inlet, bend the accel pump levers, etc.) Nothing that you can't do, but some guys might struggle with those modifications.

Hey, thanks, Andy. I'll call them later, and inquire on mods for E85. I read that the main wells in the QF 8896 conversion blocks were larger, but still had the idle tube. Thanks again.
p.s., none of the issues you stated seem that unreasonable. Thanks again.
Leigh Vail

I switched over to the 5120 blocks a few years ago. you will need different accelerator pump arms and longer bowl screws.

I am not a big fan of idle tubes in the main well.

Thanks for the pic and experience. I really appreciate it.