the 7wsm is a light weight gun? And you want a heavy barrel gun? If so go to www.gunbroker.com click on modern rifles. than type in left hand in search box. I just looked 3 pages of lefties.There are 4 m70 in 7mm rem mag, also one in .300 win mag.Good luck.Also a few Weatherbys if you like them.
Did you search gunbroker? They also list alot of remingtons. Especialy the ultra mags.
If you want to go cheap, but very accurate, look at the Savage rifles with accutrigger.i have one in .223, shoots great.They have a .308 with this trigger, and heavy barrel.
how far you plan on shooting? The 7mm rem mag is good out to 1200yards.7mm STW 1500 yards. The ultra mag should be in this neiborhood.( These #'s are from Dead On, by Tony Noblitt, and Warren Gabrilska)