Great info there Simon - timely for me, also, as my GR1 kit is coming to me, and the only holes I wanted on the top of my Gretsch copy (apart from the f holes), were the bridge post holes, cos I figured, they'd get them right! Maybe I should have asked for no holes?!
I was toying with the idea of using a rosewood, or ebony jazz style bridge, which I still could do, if the holes are indeed off on mine.
I actually bought one of those schaller adjustable roller bridges, because the pickups I'm going to use have really wide pole piece spacing - 56.5mm at the bridge, now, I wonder if the post holes are correct diameter, also...
I should have researched more - rolls eyes...