I haven't had any problems with old sinks--found my kitchen double-sink next to a dumpster--when I got it, I added new drains and faucet with no problems. Plumbing connections were compatible with modern standards.

I installed a '20s sink in my bath when I moved in to replace the one there, and also had no problems with parts connecting to the original faucets. For both projects, I used flexible lines to connect to the old copper piping, since I tried soldering before and had no talent for getting it right.

There is a picture of the new kitchen faucet put in several weeks ago on my 'House Pics At Last' thread.

Try Renovators Supply for variable spacing faucets.

I'd stay away from Renovator's Supply--I've had problems with everything I bought from them--usually bad workmanship.

My old kitchen faucet was from them--within a couple years it started leaking around the spout, and the 'tarnish free' brass finish developed pitting and corrosion.

Some glass repro shades I got for some electric fixtures were unusable because the rims going into the fixture were so thin that they broke when I tightened down the screws even barely hand tight.

By and large, there are better places out there to get the same stuff, you just have to look harder.

In our previous home, a 1916 A/C house, we took an old Kohler pedestal sink and used it in the powder room. Had it refinished by Perma Glaze. 10 years later it was still in great condition. There was no issue with the plumbing and we used a Delta widespread faucet that looked great.
BEFORE: