Yes, your '47 wheel will fit the '40 drum, but as has been said, the
lug studs on the '40 drum will be to short for a safe fit of the '47
wheel.
The '40 and the '47 wheels have different styled lug nut holes !!!
Click on pics to Enlarge
!st pic is '40-'41 Ford Wheel... 2nd. pic is '46-'48 Ford wheel.