Have a Favorite (1915) with a pitted bore and thinking about lining it (1/2" liner, .219/.224 bore/groove, 1:14 twist), and chamber for 22 WMR.  The Stevens action is weak, but both the LR and WMR are SAAMI rated at 24K PSI.  With virtually the same rim diameter, the thrust should be the same.  I'm thinking this could be a good way to make a old single shot rifle a better varmint getter.  Am I on the right/wrong track?

Even though the rims are close to the same size, they aren’t.  Consequently the larger rim of the .22 WMR is going to result in about 10% higher bolt thrust than the .22 LR at the same chamber pressure.  Is that enough to be a problem?  Normally, I’d say no.  Most firearms have a very generous safety margin built in.  However, as you stated, the Stevens Favorite is weak, and I would lean towards it being a problem.

I’m sure this has been done by someone before, I personally wouldn’t reline a 1915 favorite to .22 WMR. In my rebuilt 1915 favorite with modern steel hardened link pins and a hardened link, I limit my shooting to standard velocity .22 long rifle ammo to be on the safe side.

MUCH lower.  WMR factory ammo is loaded pretty close to the SAAMI limit, otherwise it cannot justify its' existence.  Bolt thrust will typically be over 1000 lbf.  

.32 Colt is more like 550 in the normal subsonic loading.  Even commercial .32 S&W Long is typically only about 750 lbf., which I personally think is too much for the 1915, although many have done it.    

The 1915 does have a much stronger link than the '94 Favorite, but there is still the fact that the vast majority put all the thrust on the pivot screw; only the few that were made before the Savage takeover have the breechblock in contact with the recoil shoulders in the frame like it should be.  Finding one of those was a priority for my .25 Stevens High Velocity project, and that's only going to be in the vicinity of 650 lbf.  (I had to pass up at least a dozen before I found one.)  

Just one more datum: the 1350 fps "HV" version of the .22LR is pushing just 400 lbf.    .22LR ammo isn't actually loaded anywhere near that SAAMI max.