don't measure hole to hole.. BHC are measured diagonally..
that's 63.6mm or 2 5/8" inches roughly.. is that correct?
Oh, and for additional precision, please measure the center of each hole, OR from the outer to the inner edge (which is the same distance)
chances are it's just the std 2 7/8" bhc as the ones I linked...
Or, on the very same page, there's a sprocket carrier with that bhc too
just in case there's no other option left
'sid