73 Duster with Cragar V-5 Black Steelies

Not to imply that these are necessarily and better but have you ever looked into Avon CR6ZZ? We can't get them too easily in North America but they're supposed to be pretty good 15" rubber.

Then again, they may not offer the steamroller sizes like you're running. :D

EDIT: The do offer 295/50/15!
CR6ZZ | Avon Motorsport