I would first get new ignition key set if you need to keep it a running driver.
As far as rekeying, it seems to be a lost art. Basically you need to find locksmith that specializes in this sort of thing, it will be pricey.
essentially on the tumbler there is a little steel cover, it holds down the pins and about 6 springs. each pin as an upper an a lower. the correspond to the position, if they are match correctly to your key, once the key is in, you unlock it.
I have to do this same thing because I want 1 key for the lock and ignition, but someone broke the ignition on F100. At some point someone did the old stick a screwdriver and broke out all the pins. but my replacement obviously key doens't work my old keys and I
also want mine to match up.
I reached out to a lock parts guy on ebay to see what diameter these are
https://www.ebay.com/itm/325205509361
you can see all the parts are there, you just have to be crafty in taking part your tumbler and matching your key.
Also guys as easy as this seems, it has become a very lost art to do. A locksmiths in LA are just key cutters like hte OP says. I once was quoted 100's to rekey a Cadillac lock. On those they just pull a number and cut a key for 35.00. I can imagine what actual rekey pin work would cost.
Also there is a locksmith on ebay that sells refurbished car lock sets with new keys, I'll see if I can find them.
here they are, maybe do a contact seller
https://www.ebay.com/sch/i.html?_ss...andkeys&_oac=1&_trksid=p4429486.m3561.l161211