Oxysback, that's a great find. Beautiful frame. The top head lug is rather odd, as if the framebuilder took a standard lug means for a horizontal top tube and made it fit a mixte angle by cutting and bending it. I imagine it's still strong enough, just looks like it has a big crack. You've got a steel cottered crankset there with a French bottom bracket. Could be replaced if you want, but challenging to find appropriate parts. Simplex plastic derailleurs - they wouldn't have lasted nearly this long if the bike had been ridden alot. Mafac brakes - they'll stop well but squeal like heck. The freewheel may be French threaded, so be very careful if you decide to replace it on the original hub. Things you really ought to do: replace the cables and housing, replace the brake pads, repack the hubs, bottom bracket, and headset with new grease. The grease in those parts is 30 years old and doesn't really resemble grease anymore, so put in fresh before you put too many miles on this bike if you want those parts to last.
Oil is good, grease is better.
2007 Peter Mooney w/S&S couplers/Terry Butterfly
1993 Bridgestone MB-3/Avocet O2 Air 40W
1980 Columbus Frame with 1970 Campy parts
1954 Raleigh 3-speed/Brooks B72