Domingo

Whatever you please DO NOT knurl that surface area again. The factory knurl is fine but going over it I'm afraid you will create one heck of a problem. Even for a rope seal to survive on.

There are many, many factors that come into play with rear crankshaft seals and I can only go by what the info you provided as I don't have the parts in my possession. So here's a few suggestions for you to consider.

Suggestion #1
Measure how deep the groove is in the crankshaft. Mock the seal up in the block WITHOUT the crank and measure the I.D. of the seal lip. Be careful not to flex the lip when measuring. Subtract the seal I.D. from the crank groove dimension.
If it's less than .015" put a rope seal in there.
If it's more than .015" you can take the chance with the rubber seal. However, I would suggest the minimum amount of crankshaft end play so the seal doesn't ride up on or out of the groove. This will effect the dynamics of the seal and quite possibly cause sealing problems.

Suggestion #2
Have the surface welded and bring the diameter and surface finish back to spec. no need for the knurl.

Suggestion #3
Put a rope seal in there and be done with it.

Another thought Main and rod bearing clearances play a role in sealing this area as well. The more clearance the higher risk of sealing issues as excessive oil can overload the seals ability to stay in contact with the crankshaft surface.

I hope this helps,
Merry Christmas everyone!