Help determining correct cylinder, ring, and piston sizes

[Faustmill]

I am taking my heads and cylinders to the machine shop tomorrow and wanted to check things out with you guys first so I have a better idea of what I am talking about.
The book says the standard bore size is 3 7/16" which by my calculations is 3.4375". It also says that the piston "clearance" is 0.0015 to 0.002" with a wear limit of 0.007".
My present bore size is 3.442", which is 0.0045" bigger than stock. You can get rings in +0.010" increments (i.e. .010 over stock, .020 over, .030 over, and so on). Same with the pistons. My present piston diameter is 3.414".
So I think I should tell the machinist to bore the cylinders out from 3.442 to 3.4475, which would be 0.010 over the stock bore size.
I assume that "piston clearance" means that the diameter of the piston should be .002 less than the bore diameter -- is that what this means? If so, my present piston clearance is .028 inches (3.442 - 3.414 = .028) which is .026" more than the .002" that the specs call for. This seems like a lot. So I guess I need bigger pistons.
They sell the pistons and rings in 0.010" over sets and I am thinking this is where I should wind up. Do I have this right? Sorry this is confusing. Thanks.

[1950Panhead]

Buy a set of .010" over pistons, take pistons and cylinders to shop, tell them you want .0015 clearance.
Honeing cylinders without pistons is crazy cause pistons vary.
Jerry

[Panacea]

Are you using cast pistons? I went thru a few sets of Wisco forged pistons on my 49 chopper until I figured out they need more clearance, especially if you don't let it warm up before take off...

[Faustmill]

Jerry, What you said makes sense to me. I will get the pistons before honing anything. I have used this machinist before and have confidence in him -- he probably will tell me the same thing.
Panacea, I plan on using cast pistons from the J&P catalogue that come with matched rings and wrist pins. These pistons are "cast alloy with a steel expansion control strut cast in".

[nmaineron]

I would let your machinist measure your bore...Not so much for oversize and wear but for straightness, your numbers indicate that .010 should do it but if they aren't straight you may need .020...hopefully not...

[Faustmill]

nmaineron -- more good advice! The machinist's readings called for 0.20 over whereas I thought 0.10 would do it. Thanks.