Before you build anything go here and read:
7mm Cartridge Guide within AccurateShooter.com
I have in my inventory a 7MM WSM and had I not had my head up my azz and followed through with more research prior to building up this rifle I would have selected the 7MM Short Action Ultra Mag. It will use less powder but give outstanding performance shooting the 185 gr. VLD bullets and WILL GIVE longer barrel life than the 7MM WSM! The WSM has one problem that I do not care for which is a very short neck and to be able to use the magazine in the short action rifles the bullets have to be seated too deeply within the case. In over 60 years of long range shooting and hunting I have always found that best accuracy was obtained with the pressure ring of the bullet being slightly forward of the SNJ aka shoulder/neck/junction. Shooting Nosler 150 gr. VLD bullets through this rifle I have, in order to use the mag well the base of the bullet has to be seated well below said SNJ. With that being said...the accuracy of the rifle is superb. I fired 12 rounds through it last date from 600 yards in a ladder test and total vertical dispersion was 1.750". I do wish however that I had gone with the 7MM SAUM for the above stated reasons.
Good luck sir on your build!