Over the years, different dimensions on these cars tend to 'evolve'. Sometimes that is because of drawings being made from hand-made measurements of a part, and yet other times from modifying components to accommodate the different design of an evolved newer mating component.
The PCD (Pitch Circle Diameter) dimensions which Dominik shared, as he indicated, are accurate for an original CSX car from AC and, I believe, also a CSX continuation car from Shelby.
The drawing below is the PCD that Superformance uses for its steering hubs. The bolt holes of the two drawings are offset by 90˚, so you need to rotate the SPF drawing 90˚ clockwise to get the same fastener orientation as in the CSX drawing.
When you rotate the SPF drawing to mirror the CSX drawing you will see the dimensions are 'essentially' the same but still different. Remember my comment about 'evolving' dimensions.
Which is historically correct is less important than which will fit your car! You have an SPF car so your bolt pattern is the one I have included in this post. If you use the fastener locations in the SPF drawing, you can rotate the hub orientation to optimize it for the placement of your new fastener locations.
The SPF hub uses a VW steering hub spline that has 31 splines so you have the ability to make minor adjustments to the hub clocking in 11.6˚ increments (a single spline offset) to regain proper steering wheel alignment for driving down the highway.
If the new wheel you want to use has a bolt pattern that will not allow you to modify your existing SPF hub, then you need to make a new hub and essentially start from scratch. The necessary dimensions are in the print above to allow you to do this. When you do, remember to re-spline the new hub for a standard 31-spline VW steering column, which is what is in your car right now.
The fix you are looking for is not that difficult, but again, it is not a walk in the park. That said, you now have all the information you need to solve the puzzle.
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