Check with Tornado Technologies as they can typically thread most barrels or explain why something can't be threaded. ADCO would also be a good place to email. When I was looking at threading a Beretta 84, ADCO said that they could do it.
I think I've heard that a P38 can be threaded but a P1 can't be threaded due to barrel construction, but I don't have any data to back that up. It could also be that I'm not remembering correctly so take that with a grain of salt.
I recently got a Makarov suppressed and have to say that while it's fun to shoot, it does have its quirks. The major issue is the massively increased back pressure. Even woth a 21lb heavy recoil spring, some of my magazines spontanelusly self-eject after a round is fired (and some don't), and accompanying this is much more powder residue coming back at the shooter. Now I know that blowbacks aren't exactly clean, and shooting anything suppressed is likely to spit powder back at the shooter, but After only 25 rounds I had quite visible powder residue going half way up my forearm and had two stripes (think slide bite but with powder residue) along the web of my hand.
Keep in mind that the Makarov is a blowback and (I believe) the Tokarev is delayed blowback, but you may still have some of these issues as neither of these guns were designed to be suppressed. I am also using a wet/wiped micro suppressor on the Mak (Thompson Machine Poseidon) which should have more backpressure than a typical full sized can. I would not expect the same "comfortable" shooting as if you were shooting a Glock or Sig, and reliability would very likely be negatively affected.
On the other hand, there's nothing more fun than showing up to the range with a gun that no one has seen suppressed before
