Gas Mileage???

brasil
If I understand your ramblings correctly, you ended up at ;16/34@ 3500plus10 ported
If your curve starts at 1000 then your dizzy is kicking in 18* in 3500 less 1000= 2500rpm. so that would be 18/25 = .72*/100rpm. I like that number. It means that at 2500, the engine is seeing;(2500 less 1000)/100 x .72 =10.8 degrees plus your initial of 16* =27*. That puts your power curve just a little ahead of mine,( which works very well for me, on 87E10.). To that 27* you then add the Vcan of 10 =37* for cruise timing.
If your engine will not accept 37* of cruise timing, something is wrong.
The first place I would look is the timing lite and the second is the TDC mark.And the third is the engine running temp.After that is the Squish. There is a squish dimension that actually makes things worse. We all know that that squish from .030 to about .050 works pretty good, We also know than squish greater than about .080 is no squish at all. It's that in between zone that can cause trouble. IIRC your cylinder pressure was quite high. And that would compound the problem. That is to say; high cylinder pressures and intermediate squish makes trouble. If your carb is also sucking hot underhood air, that's a triple whammy.
Now I tell you what; up to this point you haven't offered your cam specs.Nor your true compression ratio. So if you post those up, I will attempt to back-calculate your Dcr. But I cannot see into your engine to measure your squish.
These are the numbers I need; exact bore and stroke, rod length(or stock), Static compression ratio OR average cylinder pressure from a known good gauge, and the intake closing angle. If you don't know the intake closing angle, then I need the advertised intake-duration and lobe displacement angle.If you don't know any of that, how about a cam part number, and I'll go look it up. What's the big deal about the Dcr? well it could help to figure out what is going on.