“I know it seems to be the answer to all “which steel HT?” questions, but I think this might be a reasonable suggestion – if you use nice big 2.5 or 2.6in tyres anyway.”
It does seem a very versatile frame, as long as you aren’t wedded to super short chainstays, ultra low BBs or super steep seat angles!
BB drop at sag with a 100mm fork will be 64mm, head angle 66.5, seat angle 74.5; or static it’ll be 56mm BB drop, 65.4 deg HA, 73.4 deg SA (basically the same as the sagged 140mm fork geometry).
You don’t even need big tyres as the BB is fairly high (in current terms) with 29” tyres, presumably because Cotic like pedalling up rocky trails in The Peak and because it’s designed to work with smaller diameter 27.5+ too.