It's "my bike" so I can do what I want, I know. However, I am wondering what the general consensus is on drilling an 8 mm or 5/16 hole through the inside brake holes of a of a '70 R. International...(?)

If it helps it's for the Paul Racer center pulls - https://www.paulcomp.com/racer.html

I have a '72 Raleigh International, no way I'd drill the brake mount holes. Most of my bikes I just do whatever I feel is necessary to make them the most functional, but my International is one I won't modify. Like you say, it's your bike, but for me the International is the most classic bike I own, it's the one I won't mess around with. Everyone has a different perception of what's "right" for their own bikes, though.

Find a set of Mafac Racers. Does anyone else find the Paul's Racer aesthetically displeasing? I really don't like the look of the bulbous ends.

+1

I have to agree about the Pauls. They're ugly, but I hear that they work well.

I like Mafac Competitions much better than the Racers.

I wouldn't drill it.

Yeah, I don't think I'd drill an old International... unless you know that's exactly what you want to live with the rest of your life. As stated, Mafacs stop pretty well, though also ugly if you ask me. Why not a pair of the Tecro long reach sidepulls?

It would be a lot smarter to modify the caliper you want to use than the frame. If you have enough mechanical skill to correctly counter-bore a recess in a fork and frame, I'm sure you can figure out how to swap a longer bolt into a brake caliper, yes?

Weinmann center-pulls were used on the bike originally. I have found no advantage over them with the Pauls as far as braking efficiency, so I would never bother buying them in the first place. But, if you're completely modifying and/or re-painting the bike, and want something flashy yet retro looking, sure - why not. Personally I think they are truly ugly and they look like crap on the bike in the photo. The Dia-Compes from Rivendell near identical design to the originals (only better now) are much nicer looking, and I know you can just toss on a standard long bolt for the front.

I suspect the Pauls are really targeting newly built bikes which the owner wants to present with a faux or pseudo-vintage look, but on really a modern ride... say a Rivendell, complete with STI brifters, but at the same time fancy old fashioned looking lugs.

If you're hoping to keep that bike with its original factory paint, it doesn't make much sense... In fact, drilling it would instantly decrease any future collectible value of the bike dramatically - if that were of any possible concern.

As for drilling in general... I have definitely drilled bikes, even my own, and I see nothing wrong with it. For example, if it were to use modern dual pivot brakes which are ONLY available with recessed mounts. But, I would not do it on something I would plan to keep or pass along in nice "original" condition, just bikes which I intend to mess with considerably and not worry about future value.

Your bike, your call...
Just me retro-grouch green

I have a Raleigh Professional that a numbskull former owner drilled out the forks on for recessed. So now, to have an aligned front brake I have to use a recessed nut and pivot on my Campy NR brake. I bought the frame alone on ebay and no one bothered to mention this.

You can't go back and un-drill it.

Don't do it!!!

Leave it alone.

I am in the middle about this, front fork, tolerable, but the chrome will be compromised, worth thinking about, back side of the fork is a high damp area from time to time.

As for the rear bridge, do not, the bridge is not reinforced enough to hold it well, think about how it will assemble, not good.

Drilling a front only would still allow modern caliper use for the most part, rear on the front, with the allen nut, front on the rear with a nut, there are some exceptions, and I have seen extended length allen nuts that could make this easier, if you had Campagnolo differential calipers, but the International has such long reach anyway, not many choices.

Pauls center pull calipers are indeed a bit clunky in the lower regions, the limits of easy CNC programming at work possibly, styling? Who needs Styling?