Wheel Bolt pattern conversion 5x5 to 4-3/4
 

I may also post this in street section:

Seeing all my other cars are 4-3/4" bolt pattern and I have many wheels to choose from I'm thinking maybe I should change over the 67' GP big 5x5 pattern.

The 67' Grand Prix is drum all around and all new brake system.

Any thoughts on the least expensive way to change it over and what GM stuff is compatible?
Thanks
Jeff

Since you asked...
I have zero knowledge on interchangeability...but...

Since you are a machinist (I am not, but have used some of those machines).
Press out old studs and drill 5 new stud holes in drum/hubs. Not sure of easiest way to do this. You may need new studs on hand to make sure of stud hole size. My machinist buddy had this fixture that clamped to a mill table. You could somehow attach stuff to it and rotate or accurately how ever many degrees at a time to drill/machine a hole where you wanted it...
I bought a set of 12" rotors and spindles from a 77-up full size GM car that obviously had the 5X5 bolt circle. I am relatively sure these spindles will fit my 77 TA without modification.

My plan is to attach each rotor to the table of my drill press. Then set a 5X4-3/4 pattern wheel over the rotor (the wheel will clear the round drill press table. I believe a 5/8" drill will slide tightly through the lug holes on the 4-3/4 pattern wheel. I only intend to make a spotting for each hole. The remove wheel and progressively drill to size needed for new studs!
Sounds like corn cob engineering, but might work...

Maybe one you 67 you could remove entire spindle to do something similar. Do you have new ball joints? If not would be good time to replace. You could also make measurements of you spindle for possible interchange rotor spindle setup.
I am only describing all this, so hopefully you might have a better idea...

The rear axles would seem a trickier deal to make happen...
My buddy has this monster radial drill press. He didn't really want it, but his first (and embarrassingly low bid bought it, at an auction). It is handy for goofy stuff, possibly like what needs to be done to your rear axles...
Only bad thing about his shop, he's 1-1/2 hours away. I have not been able to go there to do any work in a long time....

I guess I could start off by simply doing the 4-3/4 B.C. on the front drums.
And I am replacing the lower ball joint boots and get aligned so it can be driven.

I'm kind of curious about this myself. It would be nice to find a direct replacement axle, from ????? that had the 5 x 4.75 pattern already..

I'm sure you can get axles new from Curry or Strange 30 spline.
I am not sure on another GM axle, I would have to find out length of other rears like for an "A"-body.

This.

This is how we converted our ‘63 Tempest to 4.75” bolt circle ( the new holes are placed 1/2 way between the original holes).

You can also use a brake drum or rotor as a fixture to spot through.

K