It may be a new crank but make sure that the end of thr crank is not damaged, it is easy to get the seal surface out of round by over tightning the flywheel bolts and spreading the end of the crank by using a rattle gun on the bolts, you should use a micrometer to measure it properly. Also use a speedy sleeve it can be fitted with the motor in the car this will give you more pressure on the seal, use an original Ford seal as well.

has he tryed puttin some sealer round the outside of the seal could have a score or an out of shape housing