[PDUB]

Are you looking for the original style as used in the small block Fairlane/Cobra or do you want a version used in the Mustang?

I have a couple of complete sets of the original Fairlane/Cobra style 289 mounts and I may have one complete set of the original Fairlane/Cobra style 260 ones... not sure. All of these are rare as hens teeth and fairly expensive, but, as you've found out, the 260 ones are more rare.

I believe the smaller ones are about 6" on center, for the mounting holes to the block, and the larger ones are about 7" on center.

Let me know if you want me to look for them, or if you are looking for something different.