40 degrees initial!

@Hysteric
I hear what you are saying, and do agree. But I'm just telling how I got 32mpg with a 223* cam in a 367. For this exercise I used a 600 model 1850, and just leaned it out and poured timing on it to keep it running,and geared it to 65=1650/85=2040.
To do that, I collected a series of very thin wires from IIRC about .006 to .012.. Then I accessed the IFRs, which were at the top of the wells, and did what I had to, in terms of leaning it out. I used the dial back to determine the timing she liked, centered around the cruising speed, and built the curve accordingly.
Since the secondaries were disabled, this could have been done with any 2bbl, and even easier with a meteringrod carb. This was a spur-of-moment exercise,done for a specific roadtrip; the engine was already making great mileage with a 750DP; I just wanted to see what could be done with the old 1850, that was gathering dust in the shed.

Since then, I have obtained a Dual-Port and a small TQ, and one of these days, maybe ........... I'll get around to doing something, but I thing this present world wwill fade away first.

A smaller carb helps the vapourization. Try the TQ you might be surprised by what it does.