Jerry - the ones I have seen are crimped together, not bolted. They could still be disassembled, repaired, and re-crimped, but why bother? If the manufacturer has no more integrity than putting out pumps with the wrong springs, why should we believe the rest of the pump is any better?
Good ones CAN be obtained from Then & Now.
40 years ago, I hand-built some special tooling to open the crimp on the vacuum motors used to operate the secondary carburetors on GM tri-powers, and then more special tooling to re-crimp them. While the arms were different, the diaphragms used in the vacuum motors which opened hidden headlights were the same. One could open a tri-power cannister, re-electroplate the cannister, remove the arm from the dead diaphragm, open one of the headlight cannisters, remove the arm, put the re-plated original arm on the new diaphragm, and crimp the cannister back together. I probably did 75~100 when we were restoring the tri-powers.
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!