.219 Zipper sounds like the way to travel here.

Cheap and plentiful .30-30 cases, cheap and plentiful .224 bullets.

I have never shot a pig with a .22 cal rifle but over on my plantation I've shot hundreds and hundreds of ground squirrels with .223 {50 and 55 grain bullets} 5.45 and I've used the 5.45x39 with 60 grain bullets on stock-chasing dogs and butcher stock and I know I would want a wide variety of bullets available to me, particlularly in the heavy weights for your application. All .224 bullets are not created equal with some quite frangible and others much tougher. Your handloading options would be far greater with .224 than with .228 though factory ammo for the Zipper would of course not be available.

I'm thinking that the Savage HP runs at close to 50k PSI for 3000 fps with the 70 grain bullet, too, and most handloads that function well in the 99 are running a bit under that, closer to 2800-2900 IIRC. Come to think of it, a minimum taper, blown out "Improved" .22 wildcat based on the .30-30 case might be a winner also.