I've had decent accuracy with under max loads of H414 and a SST 139.
4350 is a classic powder for the 7mm x 57, may work here also.
If your goal is to cut the velocity, you may want to try a heavier bullet.
http://www.ballisticstudies.com/Knowledgebase/7mm-08+Remington.html
I quote: "Heavier 154-162 grain 7mm bullets often produce the most consistent results in the 7mm08 across a wide range of game body weights and ranges. The only downside of this approach is that at a theoretical level, the lower velocity of a 154-162 grain bullet seems to go against everything hunters have strived towards for the last 100 years- high velocity as a means to produce fast killing.
Each cartridge has its own performance parameters and using a slower, yet higher BC bullet in the 7mm08 does not in any way remove killing power or limit trajectory within this cartridge’s existing limitations. This is not the same theory as the slow moving heavy bullet practice relative to big bore performance or 20th century ballistics theory. Rather, it is simply a method of utilizing current bullet designs, particularly, the sleek, soft 162 grain A-max. The A-Max allows the hunter more error with shot placement at extended ranges as rear lung wounds are usually so severe that game cannot move far from the point of the shot. At the same time, velocity from the 7mm08 is so mild as to not cause shallow penetration with point blank range raking shots."
