Eh... I wouldn't use the rockguts. Even fellwaters are pushing it for model size in a game where, for the longest while, you needed to be mindful of both the model's base size (no bigger than 40mm wide) and the amount of space it takes up laying down on both its front and back sides (GW's token "attempt" at rectifying this is middling at best).
The Fell water are definitely better, but the rockguts just got on the 40 mm bases, and with the new GW tokens, or other rings Like the Charlie Victor ones it's still very playable, but I get what you mean. They are quite a bit bigger than most blood bowl models
Was it a really old sculpt? You guys have 140 members in your gaming group? All local? How can you promote it if you have never at least given it a chance?
You're right. Using the picture you provided, I did some digging and it looks to have been released in 2019. https://blood-bowl-miniatures.de/miniatures/games-workshop-6th-edition-big-guys/ That guy would look fine alongside the troll I already have, too bad Games Workshop discontinued it. Maybe one will turn up on Ebay for a decent price. I doubt it, but maybe.