Topend Rebuild

I am currently rebuilding my 2001 CR250 topend. The cylinder is marked an "A". I ordered a vertex piston kit, but they sent a "B" piston. I see that it measures 0.010 inch larger than the "A" piston. Will the "B" piston work in my engine? I checked Eric Gorr's site and it talks about oversize pistons and this is what it said
"must measure the cylinders bore at the smallest point and allow .002 inches clearance between the piston and cylinder."
If I have the 0.002 inch clearance will I be ok? What if I have more? What is the range for the clearance? Thanks in advance.

I measured both the cylinder and new piston. The clearance at the bottom of the cylinder would be 0.0018" and the clearance at the top of the cylinder would be 0.014"
The sheet that came with the vertex piston specifies 0.0025/0.0030" clearance.
Seems like my clearance is too small or will it work ok?