1960 GMC 305A v6 hard to start

[AngryPirate]

So, I'll have the battery at full charge and it may have been running 2 hours before, but I still need to either put the charger on "boost" mode or/and get a boost from another running vehicle.
I know it's a big engine, but man, it should be able to start more easily than this.
Perhaps the starter is bad and drawing too much juice to work efficiently?
I've re-polarized the electrical system as well.

I am forever having to spray quick start or dribble gasoline into the carb while trying to start it with a boost

I'm at my wits end trying to figure this one out.
Would finding a higher torque starter be something to consider?

There doesn't seem to be a short anywhere on the chassis (I tested for this).

So here's what I've done so far:

- had the generator rebuilt
- new AGM battery (775 CCA; 140 MIN RC at 25A)
- new cap & rotor
- replaced points with Pertronix Ignitor II
- new OE ignition coil
- replaced started with rebuilt OE starter
- new OE fuel pump
- new wires
- new fuel tank & filter
- new OE voltage regulator

I really shouldn't have to use anything outside of what was OE just to get it to start fairly regularly, I would think.

Thanks for any ideas to try.