Wobbly,
It’s a bit late to note now, but the SKF (Ex-Chicago Rawhide) catalog lists 45x75x8 and 45x75x10 radial shaft seals. Also, 55x75x8 and 55x75x10. Probably available from a bearing supply house. Also, your 73mm OD seems to be completely non-standard--could it have been 72?
If you want to know more about seals than you ever thought possible, take a look at their pdf download.