i have a custom fork made by orlowski for my pompino and it's 380mm , i always had problem with the seat tube being to slack with a 400mm fork. with the 380 the bike handle muche better for me and the builder said there is space for 40mm tyre.
Fair. Personally I'd go for a shorter stem, but hey even with a slightly shorter fork it'll ride like a bike. Not to my taste (geo) but not outrageous I guess.
Why are you going for a fork that will be shorter than the standard? Will be a pain for tyre clearance and possibly handling