I have a pair of .22-250s I have been using for about 25 years. The .22-250 can be a long shooting rifle. I own one pretty much out of the box Remington, and the other is a full out 1960s technology bench rifle. As different as the rifles the rifle scopes are certainly much different also to match the capability of the rifle. Your choice of scope can either add to the rifle's ability, or greatly limit it.
I highly suggest at least a 10X scope, because the better you can see the better you can shoot. ( that is an old quote of mine ) The other major consideration is that the .22-250 you speak of is likely a bolt action rifle. So I believe for best accuracy anything that can be done to stiffen up the receiver, since it has that large chunk removed for the ejection port is a good thing to do. I would suggest then choosing a one piece scope mount base. One that spans that ejection port opening with steel. Now, I agree it would be difficult to truly determine how much gain is there, but, I try to gain every bit I can. And the cost is little different to go with a one piece. Then buy the best rifle scope you can afford to get the best out of that rifle. You WILL in the end find you are very pleased you spent till it hurts now, for years to come owning a deadly outfit like what a .22-250 rifle is for varmints.
I prefer Leupold or Unertl, but Nikon, and Zeiss have began making top notch stuff now. I have a stash of the old Lyman Super Target Spot and Unertl external adjustment scopes and used a Lyman on the one rifle. The Lyman offers a larger field of view. I highly suggest, if you ever see one at a gunshow, buy it. Bear in mind you will most likely have to have some work done on the mounts to have the scope as new. Many offerings to even modify the internals too.
Bottom line, spend till it hurts now, be very happy with your rifle for eternity. :-)