Busted fork seals on an old trials bike.

The bike I'm doing up is a 1972 250cc Ossa MAR. After recently getting all the cablework redone me and the old man tested the front suspension, low and behold the fork seals had degraded. I understand redoing the seals is pretty challenging, not only technically but also finding the right sized seals. If anyone has any advice/tips or knows what size seals I'd need or where to get them that'd be great.

I've posted on here a few times for advice on fixing up my old mans bike and so far you guys have been a great help.

Busted fork seals on an old trials bike.