I have a 300 SAUM and really like it. Model 700.
I do not own a WSM, but I believe the case capacity makes the WSM a slightly better performer (50fps on average). WSM is slightly longer though.
I have found 5 or 6 different bullets that shoot sub MOA in mine.
For a Model 7, don't worry about loading it longer than the magazine. With a factory tube it will have quite a bit of freebore with most bullets, but I think you can get away with that in a short action round and still be very accurate. Mine likes middle of the road 30 caliber bullets (165 - 180 gr). I plan to play with single feeding the 200 Accubond, but at magazine length it was at best around MOA.
Try 55 grains of Varget behind a 168 Barnes TSX at magazine length for a great little point blank round (1.2" @200 yards). Use Remington 9 1/2M or WLRM primers as Federals did not do well in mine. Use a bit more 4350 for faster loads. For most loads you could fill the case with 4831 or RL22 and still not attain high velocities.
Use this info at your own risk, but it worked for me.