For a towing motor, I'd stick with the stock rockers. You already have them, so they're free. Full rollers are really only beneficial if you're revving over 5000 rpm on a regular basis. Your cam already has a lot of lift, so I wouldn't bother with 1.6:1 either.Good tip, thanks. I was curious about that anyway. I guess I'll use the 1.5 full roller rockers that cost $400 instead.
I looked up your cam specs: 210/214 duration at .050, .474/.474 lift, 111 LSA.
Internet says stock L31 specs: 191/196 duration at .050, .414/.428 lift, 111 LSA
That's definitely going to need a tune, but you can get it running and minimally driveable on the stock tune.
Out of curiosity, did you call Comp Cams and get that recommendation, or did you pick that cam? When I bought my cam I picked one myself, then second guessed and called Lunati. The guy at Lunati talked some sense into me and I exchanged my cam for a much more suitable cam.