Small Bolt Pattern Wheels Don't Fit Wilwood Disc Conversion

I purchased the Wilwood Front Disc conversion for A-bodies with 9" drums. Talked with PST and they said the kit should fit with my wheels. I have 15" Steel Vintique Wheels with SBP. The problem is when I tried to put the wheel back on after installing the disc brake kit, the hole in the center of the wheel is not large enough to fit over the Wilwood hub. The diameter of the hole on the wheel is about 2 1/4" and the hub tapers to around 3". They include a 2mil spacer, but I can't even get the lugs through the bolt holes. Do SBP wheels even exist with a 3" center hole? I called a machine shop and they said around $250 to make the center hole larger on my current wheels. That seems like a lot of $ and i'm not sure if that would compromise the integrity of the wheel.
1) IS the hub configured w/the SBP ?
2) Is the hub fitted with 1/2" or 7/16" studs?
3) There is no "just removing 3/4" from the center" of a steel rim. The rolled hub ring will be completely removed, and one from a wheel that fits welded in, or fabbed from scratch.
I certainly wouldn't do it for any less. Yes, if One were to just chuck up the rim & cut the center out w/o doing this, the integrity of the rim is compromised. The problem is if You
do the math, 4"-3"=1" & /2= .5" from the center of the stud hole to the new ID, w/a 1/2" hole that only leaves 1/4" of meat & no room for a lip & barely a socket over the nuts.
4) Every wheel is different, I'm sure calipers clear certain 15" rims, but not all....of course the spacer sounds like they knew they were tight & needed.
5) What ride is this & what is the intended usage for it? You may have to sw. to LBP, but why they would even sell those this way....................