I know a carb guy with a keen eye can tell the difference from the base. Not my carb, thats why im asking and owner has no way to measure anything.

Older quick fuel that has no marking on it. Edit... found a stamped number in the carb body... might tell the size, not sure.

Call quick fuel for more help

The divider between the primarys and the secondarys looks like it's thin as a dime. I say 850.

Cab, You know moparts is better then most tech lines.

Thanks John Brown.... thats sorta my thoughts comparing it to my QF 750 base.

The carb in the post I asked about has a number stamped on the carb body that starts with 850XXXX...... the last pick is from a motor trend article of a known 750 stamped 750XXXX so I THINK thats how they were stamped at one time???

has 850 throttle bores.

Looks like big bores to me, too - and I would guess that the bore measurements would be = to equivalent Holleys.
It might be that the carb was assembled from parts, though, so it's worth also checking the main body (venturis).
Other clues might be the accelerator pumps, nozzles, and jets, if there's a reference chart for that brand.

Does it have standard boosters or annular boosters in it? Annular boosters will restrict the CFM that can be drawn through it