While it's true that you can beg/borrow/steal an NR triple and copy the drilling, it's also true that is no oversupply of THE UNIQUE 36H 100 bcd chainring made by campagnolo, which imho, was a rather silly thing for them to do. Also, I think the limit is 31T or 32T if you can get the super-rare Merz rings ( I loaned Jim Merz my 36T ring last year but he decided he was never going to make another run of campy rings with his remaining blanks.)
You would probably be much better off to drill using a modern bcd, such 94 bcd or 74 bcd.
I would think that if you can lay a crankarm back-to-back onto the spider to mark the hole centers, then you can probably lay a chainring back-to-back on the spider and use C-clamps to hold it down. Then, mark the hole centers, perhaps using an inner chainring bolt and a skinny pencil or punch to center the hole.
The penalty for a minor bit of misalignment would be a need to slightly file chainrings every time you install new ones to make them fit. As this is a common thing to modify 102 bcd ofmega rings (which can be made into campy 100 bcd by filing the insides by 1mm on all 5 holes), and to modify 130 mm shimano rings (which can be made into nervar 128mm rings by filing the insides by 1 mm on all sides), a minor sub-mm error should not be a big problem.
- Don Gillies
San Diego, CA, USA