You can buy replacement lock cylinders, with keys, from the usual suspects (Moss, TRF, etc). Or, if the numbers are present, have keys cut to the number. Here's a couple of places that I believe can cut to the original numbers:
https://www.britishcarkeys.com/
https://www.key-men.com/
You could probably also ship them the lock cylinders and have them match keys to them.
What I did was to buy the blanks on eBay, and cut them myself.
Or, yet another option, buy the blanks and take them to your locksmith. Chances are very good that he can cut them, they usually just don't carry those blanks. The hardest part is getting the locks apart, and that's usually pretty easy. You'll have to remove the ignition lock from the dash, and pick it once to unlock the cylinder, then there is a hole that lines up so you can push the pin that releases the cylinder from the lock body. It's been a long time since I've done door locks (what good is locking the door on a ragtop? My TR3 doesn't even have handles
), but IIRC they are very similar.
Check YouTube for any number of videos on how to pick locks.