If it were me, I would be very upset if I got a block back from the shop and the bore varied .0025, from what I asked. That's a lot and I would NEVER use them again, for anything!
If you research 4032, you'll find that one of the main differences with 2618, is that it it is more brittle, in comparison. The other, is that it does not expand at near the rate of 2618. You can get away with with more clearance and abuse with 2618.
Again, if it were me, I'd never feel comfortable with that one cylinder and would probably hear piston slap, every time I started it, where it was there or not and I think the OP, is indicating he feels the same.
So, if time and money is no issue, I would take it to a GOOD shop and and get a good job done.
I'm a old mechanic and have seen a lot of knurled pistons. I have nothing against doing that but, would really hate to do it on a brand new piston. Also, the knurling wears away over time.
Last, if that extra .002, really won't matter, call RaceTec and verify that.