Ford made the front of the cam shorter in 1942, and made the distributor deeper to match. There is a piece made that fits between the later cam and the earlier distributor to fill the gap. I'll see if I can find a link to one.
Edit, part number 11A-6280 available from several vendors including one who regularly contributes knowledge to this forum:
https://thirdgenauto.com/product/193...termarket-cam/