Anyone make 26.8 seatpost longer than 410mm? 450?

Got a frame that i’ve realised has answered all my prayers for a bit of a do it all – lightish, tough, long enough top tube for comfy xc position but can be thrown down local DH runs. I need about another 25mm to get spot on leg extension. I dont want to just pull it past the min insert mark and hope for the best as it flexes a lot as it is (Race Face XY post) so after a post thats maybe 450mm?

Anyone any ideas? I’ve tried the usual suspects but no joy.

Roox used to do 440mm posts.