Wow, you really lucked out on finding this Comp in such lovely condition, and still with the original build intact!
Coincidentally, I also acquired a '73 Comp from another user on the forum - same size as yours and everything. It's in decidedly worse condition, so I have no qualms about putting it under the torch for 650b conversion, but I'm also itching to just build it up with components from the parts bin.
Needless to say, I'll definitely be following this thread.
I do have a low-flange Maillard 700 front hub handy, but ideally for the Competition I would build a new clincher wheelset with either period or somewhat newer nos or otherwise very good condition high-flange hubs and I think H+Son TB14 polished rims.
I wouldn't think twice about having a nice newer wheelset built up, and also making slight adjustments to the original spec to make it more ridable. That's the whole point, after all!
Additionally, I can attest to the insane tire clearance on these framesets. Here are some pictures of a rough mock-up of my '73 with 32c Gravelkings and 40mm V-O fenders. It looks like your frameset has the same quick-taper chainstays and the sweet sloping Davis fork crown, so you can probably expect the same clearances:
The fork especially has quite insane clearance (makes 32s look like 23s!) bolstered even more by the fact that this is a 27" frameset.