Choosing the right twist rate and barrel length?
For pigs, coyotes, bobcats. Tips and advice is greatly appreciated

A 1:14" twist is the most common in a 22-250. It will shoot up to 55 grain bullets well. If you want to shoot a heavier bullet, you will need more twist. I'd get a 1:8" or 1:7" twist to shoot the heavier at longer ranges. But if you go to a faster twist, and want to shoot the light bullets fast, you can easily vaporize the bullets in flight with a tighter twist.

Up to 70 grains- 1:9" twist
Up to 80-85 grains- 1:8" twist
Up to 90 grain twist- 1:7" twist

Keep that rifle as origional as possible, best advice I can give ya!

Any thing wrong with the present barrel? I have owned 4 Rem 788 and all were great shooters, this is first time I have heard of rebarreling a 788. Then again, I don't get out often.

Is the old barrel shot out , try seating the bullets out further towards the lands, if you handload, this will tighten the groups back up . finished mine has a hart 23" full bull 22-250 1:14 twist the old 788 barrel will need a relief cut so it will unscrew the old barrel will be trash when you get done, I cut up mine from a .243 and the throat is longer to seat the bullets out. not a pig gun mines heavy br set up. 52 v max 50 nbt, jewell don't make triggers for had to do somthing else, sucks this thing would really shoot if I had an 8 oz trigger now lowest is 2 lbs. do yourself a favor if I dind't have 5/6 788s I would use a 700 action more options and inletting a 788 to a boyds thumbhole was a real pain in the ssss. keep them stock they shoot great as they are. 1:12 will get you to 60 call krieger $ 335.00 will get you a c/m heavy sporter #5 28" blank or ss cut & crown and bed the action, float the barrel done.

Why is that?
I've had it in my mind to rebarrel an old 788 243 into a 22-250. I'm not trying to be a contrarian, just curious. is there something inherient in the 788 design that makes a barrel swap a bad idea?

You knock a third of the value off that rifle when you do it, the 788 was probably one of the best rifles Remington ever made. leave it stock and just buy a 22-250.