varies
I'd think a "guide" would carry much, and shoot little. The rifle would need to compact and portable. As their responsible for their client, they'd need to shoot well when necessary on dangerous game, and have adequate caliber/power, likely a tad more than average. If your area/ quarry can't necessarily hurt you, I'd think reliability would still be paramount, so as to help guarantee collecting a trophy.
Phil SHOEMAKER (?), the Alaska bear guide, in the various articles he's either written or been featured in, has rotated through a variety of rifles/calibers apparently, when dealing with dangerous bears. But all are big bore, short and compact. Harry SELBY (?) shot a .416 Rigby in Africa with RUARK, lots of big nasty critters over there.
Rather than gut a Ruger Scout, why not just buy a Savage Hog Rifle and be done with it? If you want the big positive extractor and ejector, what about the discontinued Ruger Frontier.....all in .308.