Cam design limitations

Maybe they're not wanting to grind what you want because they feel they'll have to reduce the base circle so much to get that kind lift that a cam as long as the slant's would twist itself apart.
Have you talked with Oregon Cam Grinders, 360-356-7985
I was under the impression that if you or they had a core with enough lobe height, they would grind you just about anything you wanted.