I've been bringing a 73-74 Gitane Tour de France back to life. Since I started little more than a rusty frame this is not a period correct restoration. While I appreciate vintage bikes, my goal for this one is to upgrade to modern parts where beneficial. I also really like the look of threadless stems. So is this possible and or beneficial?

PS. I am aware that the stem diameter is .2 smaller on my bike than standard (which can be corrected by sanding)

Also just read that the French headset is not compatible. Could this be avoided by changing the fork?

If you go threadless you will want to get a threadless specific fork. Chris King makes decent 1 inch threadless headsets. However I must protest! Threaded stems are beautiful.

Velo Orange now has new French headsets available. They are having them manufactured or found a source.

Get a 1" threaded steerer to 1 1/8" threadless headset adapter and sand down the part that goes into the steerer and you can use any 1 1/8" threadless stem that you want. I just converted a Kona cruiser with 1 1/8" threaded steerer tube to use threadless stems due to much better availability of threadless stems these days.

Not period correct and some consider threadless stems ugly but they work fine and stems with removable front plates are certainly convenient IMO.

Thanks for the replies. I forgot to mention that I have already upgraded to the Velo-orange bottom bracket. Before I spend any more money I think I will ride it with the original fork/stem/handlebars for a while, then maybe upgrade later.

The rest of the parts have been scavenged from trash-day bikes. Weinmann brakes from an Austro-Daimler, which seem to fit a 700c wheel when bolted to my fork. (I expected there to be a problem since it came with a 27") Huret Deraileurs from the same bike (front derailleur won't fit due to different french tube size). Aero crank from a Lotus which is missing the 2nd chainring.

I almost have enough parts to assemble the bike. I can't wait to ride it, I have spent a lot of time repainting it, and polishing various parts.