Don’t need to shorten the hoses, just need to swap the levers over, hoping to get away without a bleed – any tips?

Do it with the pistons out of their bores a fair distance and you might get away with it.

No need to bleed

There’s a tech doc on the shimano site that shows how to do it, basically it’s remove pads, pump pistons in bit, remove hoses, push pistons back, put hoses back in.

All the time keeping hose and lever well above caliper.

Presumably you’ll still need to fit fresh inserts and olives though.

No, should get away without the olives and that, unless you’re shortening hoses.

Well you learn something new every day!

Officially you should use new olive and inserts but I have swapped a set of my own brakes without doing so. If I was doing it for someone else I would use new bits just to make sure.