Talked to my transmission guy-------

Darter6 said
It depends on who you are buying the converter from.If it is a special order they can change the converter register to the smaller early crank style to fit. Hughes did mine for a late 904 mating with a 67 crank.Didn't cost anything extra at the time it was ordered.That was back in 2004 but I'm sure they(most converter companies) will still do it.

X2. The converter company I worked for in the past did that on a regular basis. What they do is change the front (engine side) of the converter to the earlier version. Don't let anybody tell you they can machine down the hub of the newer converter. There isn't very much metal there to do that.