I got a SH 780 cheap and it horizontal strung because you couldn't tighten the main action screw properly without it fouling against a bolt lug. I've never had the chance to inspect another so I don't know if the screw was the wrong one or there was some sleeve or something missing, but it was too long. Filed a mm or 2 off it, tightened it good and snug and it now shoots real good for a cheap rifle.
The 700 actions do have a torque spec, IIRC it's listed in the manual. I guess 780's and 788 have it listed to but I never downloaded one to check.