Not certain I totally understand the problem:

Will the engine not rev up to WOT period, even with choke; or will the engine rev with choke, but not without choke.

As Joe mentioned, POSSIBLE accelerator pump issue. EASY TEST FOR BAD ACCELERATOR PUMP:

http://www.thecarburetorshop.com/Troubleshooting.htm#Acceleratorpumps

Other possibilities:

Distributor advance not functioning (should be able to determine this with a timing light).

Insufficient fuel delivery to the carburetor.

IF YOU NEED TO REBUILD THE CARB, having the tag number of the carb to supply to the kit vendor is the best way to get the correct kit. If the tag is missing, this link may help you identify the carb:

http://www.thecarburetorshop.com/CarterChevroletW1.htm

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop