The piston manufacturer should be able to tell you the recco skirt clearance for that specific piston and your engine. It's going to vary considerably with the aluminum alloy, forged vs. cast, cooling system, somewhat with the pin boss and skirt design.
Very important: the difference in width across the pin boss vs. across the thrust axis is the "cam grind" or profile. The most common cam profile is the standard Van Norman “C”. It compensates for the way the piston shape changes during hard use, and it's fixed during manufacture, and no correction for this can be made by changing the skirt clearance.
Your guess may be correct, or far enough wrong to cost you $$$.