Ooops, sorry, DP3; I just made the same comment about the PG's mass bias on your PG thread. (I think you're right and both series have a marked mass bias.)
I should dig out my Seafoam. I had it drilled label, but found the 800 grit finish a bit much. I had to sand it to 1500 grit and then put a high gloss polish on it. Haven't used it in over a year.
Your drilling is certainly MILD! but with the 800 grit finish, it should match up pretty well, Besides, you seem happy with it; so it must be reacting well.