Any "wrong" distributor will work on any tractor from the A thru the 450, EXCEPT the W9 gas and all gas-start diesels - these spin the opposite direction. However maximum power and fuel economy will suffer slightly unless the correct distributor is installed.
AFIK the various distributor timing curves are achieved by swapping springs in the centrifugal advance. So theoretically you should be able to get the correct curve for your A by installing the correct springs. However finding the right springs today may be a problem(!)