Not exactly sure what you mean. The 450 NE has a significantly larger diameter body at .540 where as the 45/70 family is .503. The rim diameter of the 450NE is .620 and the 45/70 is .610. The rim thickness of the 450NE is .040 and the 450NE is .070.

If you are referring to the difference in rim thickness, the 450NE having a thinner rim (.040) than the 45/70 (.070), there are two ways to go.

1) There is a thick rim version of 450NE brass available...now and then...which is .060 to .070, that would work.

2) Set the barrel back about 1 thread and then chamber it to the standard 450NE dimensions.

My gunsmith is setting the barrel back. 450NE brass is rare enough and expensive enough as it is without looking for an even rarer subset.