So if you want to be able to shoot to 350, consider:
1) How much elevation do you need (in mils or moa) for that range with your ammunition?
2) How much vertical adjustment (total, in mils or moa) do you have in your scope (top to bottom)?
3) Take 1/2 the answer to #2 and compare it to the answer to #1... If 1/2 x Answer2 is greater than Answer1, you don't need any cant to your rail/base. If 1/2 x Answer2 is less than Answer1, find the difference - that is the
minimum amount of cant you will need in your base to be able to dial elevation corrections to 350 yards. Note, you don't want the amount of cant in your base to exceed 1/2 x answer2 or you might have difficulty zeroing your rifle at closer ranges...
(PS: Listen to Rob, he's speaking from experience, I'm speaking of theory - I don't play with .22 rifle much and definitely not any serious distance!)