The original Favorite that was sold as a .22, by Stevens, is definately not a candidate for centerfire conversion, and not really safe for the Mag. rimfire stuff. Skinny pins and links issues.
The newer Model 30 must have been beefed up some, to get it past the liability lawyers working for the company, but I would suggest that it is not up to Hornet pressures by a fair stretch.
IIRC Stevens also labelled the Model 44 and 44 1/2 as "Favorite",in some variations, and these are much more suitable for the higher pressures nd larger diameter barrels. Of the two, a Stevens 44 1/2 action would be better.
Got a library card? Try to get hold of a couple of Frank DeHaas' books on Single Shot Rifles. He went through most of the common and uncommon models, and detailed strenghts and weaknesses, as well as suitability for conversion to other calibers.
I have had a couple oldd Favorite actions, and unless they have REALLY beefed the design up a lot, I would hesitate to use one with aa .22 Mag, and would not consider a centerfire conversion, except maybe to a pistol cal like .32 short or long, maybe.
Cheers
Trevor Jones