Scat stroker crank main bearing question xtra clearance bearings?

I don't know of any, but if you already have the MS 963-P and the shop measured correctly, just have the crankshaft ground .001" to get the correct clearance and allow use of the easy to get standard size bearings.
Since you are looking at P series bearings, I assume you are running a cast crankshaft. If it is forged, make sure they checked the radius for clearance to the P-series bearing.