So I bought an 8.75" B body housing, axles and perches for $200...

62/63 would be tapered axles. I wouldn't use those.
And I'd take a look at the splines of the axles you have, to see if they can be shortened (I'd bet against it)
If thats the case, and you can't respline the axles, I would not narrow it if I could avoid it, and explore wheels with extra backspace.
I think custom wheels might be cheaper than narrowing the rear and getting custom axles.