Question for OD&D LBB/White Box types?

So I'm DMing a LBB OD&D/Whitebox d6 & d20 type game, and I've found that converting "normal D&D" material on the fly is a snap, except for one thing, monster damage.

There is a precedent in LBB D&D (& EPT) for some monsters inflicting multiple dice of damage, such as giants.

If you are converting a post-greyhawk/AD&D/B/XD&D monster to LBB OD&D, at what point (if any) do you decide that the monster's attacks do more than one dice of damage? Or do you use another scheme.

In an encounter with a giant crocodile that was listed with a 3-24 damage bite, I decided to roll 3 six-siders and use the highest roll; but I could see rolling two or three dice for damage (4-24 roughly equals 3 d8 "hit dice" which would be 3-18 in d6 "hit dice").

I also use "latter era nice-guy Gygaxian/Master of the Game" PC hit dice; PCs roll 1 die per level, with fighters getting a +1 per die, so the PCs do have more HP than standard LBB characters.

So how do you guys handle this?