I have a Remington 700 Long Action Sendero .338 RUM, Zeiss Diavari 6-24x56, Badger Ordinance 0 cant base with .035 in shims under the back base, Badger Ordinance Rings. My point of aim to point of impact is a difference of 11 inches down @ 50 yds. What can I do to achieve max scope elevation adjustments and be dead on at 100 yds. Would a 45 MOA base work better?

Am not sure just what you are trying to accomplish with such elevation, but to begin with your optics may well have enough elevation to reach to say, 1000yds without any "long range" base arrangement?? How much elevation adjustment does your particular scope offer??
After installing a scope on a receiver you are most likely to "absorb" some 15 moa or more alone, so subtract that from the total available and if you know the trajectory of the cartridge at your desired distance/target you can then determine whether or not you need a long range base set up and how much. Again, not sure of just what distance to target you are trying to reach, but I would double check to see if your scope would work without any additional elevation mods.

Thanks MFD. I am trying to reach out to 1000 yds. The scope has 55 MOA elevation available. I have not chrono'd the rounds I am shooting yet but I am using 93 grs. of IMR 7828 with a 225 gr. Nosler Accubond. Reloading book says it should be around 3050 fps.

JCM, I hesitated to respond because I too was not sure what was going on. Are you saying that with the scope elevation cranked "down" all the way the best you can achieve is 11 inches above point of aim? First I would remove the shim and sight in at 100 yards. Second, with the information you have given, plus the BC of the bullet, you should be able to go to any of the trajectory tables available on the web and they will tell you roughly how much elevation you will need at 1000 yards (plus the intermediate ranges). Do you have access to a 1000 yard range? If not, then test out the table results with live ammo testing. I have a Farrel 25 MOA base on my Rem 700, but I have no intention (or the available facilities) to shoot at 1000 yards. Also, you don't say what reticule you have on your Zeiss. If you have the Rapid Z, you can get that information from the Zeiss website.
Peter.

Since your scope only provides 55moa of elevation, you may well end up having to use a long range base set up. Basic rule of thumb for elevation is some 3 moa per 100yds out to the 700yd line. It changes after that, but below is a typical "come up" listing for calibers such as 308, '06 or similar trajectory rounds.
100-200/2moa
200-300/3moa
300-600/10moa
600-800/10moa
800-900/6moa
900-1000/6moa
As you can see the above totals 37moa or w/quarter minute adjustments, 148clicks to reach the 1000 yard mark. Strictly a guess, but I would venture that your round would be somewhat near these come up values?? If that be true you can determine by simply rotating the elevation drum as per these come ups and find whether the scope is adequate and how much more elevation you need.(Note: Have your scope zeroed at 100 yards to do this exercise) Most likely you are going to top out with your particular scope before reaching 37 moa or 148 clicks above the 100yd zero setting. Would estimate a 20moa base be more than adequate.
Good luck.

Thank you all for the assistance. I will keep you informed of the results. I am starting with a 20 MOA base and have a 30 MOA base just in case.