Small Bolt Pattern Wheels Don't Fit Wilwood Disc Conversion

From my understanding all SBP wheels have the 2 1/4" center hole. When speaking with PST, they assured me the wheels would fit as long as they were 15", not mentioning anything about the center hole needing to be 3". Having contacted them again to ask them about this, they said I should be using OEM SBP 15" wheels and they will have the center hole of 3". I asked, where do I get those...
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1) SBP is 2 5/16", LBP is 2 13/16", the rims are not a press-fit obviously, and slightly oversize .010-.020". SBP wheels are~2.32-2.33" & LBP are~2.82"(FORD 4.5"BP rim~2.78")
2) There are rims designed to be lug-centric, but not OE steel rims w/the center cut out! Unless they're Magnums,Pontiac & Olds style Ralley wheels etc. designed to be, they're not
3) Sorry, I was addressing 416stroker about the calipers, but how do you know? You haven't gotten Your rims on yet to see, sooo......maybe-maybe not.
4) OK, crazy driving or not I would NOT just cut the center out of a set of SBP steel rims to do this. Anybody saying otherwise is giving poor advice. The only way I could see
doing that safely would be to add a "back-up" plate w/the pattern drilled thru welded to the rim at both inside & outside circumference. It could be done if done right. Not an
inexpensive job for sure, but the only way to keep the SBP & wheels you're using, of course the rears would not be setting tight on the register w/o a hub ring.