80mm width for 28mm

So, I have a mate with a large collection of 28mm ancients and medieval that are based 80mm wide by 40mm - 60mm depth. He wants play Impetus 2 but is not willing to rebase. I do not see any issue as long as both sides are the same. My questions is would you use half width for movement and ranges of 40mm per or keep the 60mm half width from the original 28mm range/movement?

Shouldn't matter, but I'd go with 40mm as there could be some issue with too much maneuverability when moving sideways

Yeah, that was my first thoughts as well. I was just concerned it would seem out of scale with 15mm range/movement.

no prob, you can use 80cm frontage. I have friends who made the same. Just play on a 15mm suggested board.
You can always add one extra 40cm base to each Unit once you should decide to use 120cm frontage.