Gizzy
A gentleman, a scholar, and a railway modeller....

Shame you don't live near me.If I had a box full of R1 I'd try to do that I think or at least lay them out to get some ideas. It's a lot of money wasted though if it still didn't fit.
I could have loaned you a few!
Second hand R1 can be brought for £3-4, and can always be re-radiused to something wider, or even straightened....