There is nothing wrong with the stock mechanical pumps as used on A series engines, but as you already know, you need the right one.
Fuel pumps for the A10 & 1200 engines interchange with each other. [Front distributor]
Fuel pumps for all of the 1974 & later engines [A12, A12A, A13ls, A13ss, A14, & A15] will interchange with each other, but not with the earlier engines [back distributor]

If I am installing a rebuilt or long stored engine, I prime the carb by removing the plugs & cranking it over till the carb is full. A side benefit is that it primes the oil system too.