I'm in the process of rebuilding the forks on my El Tigre, the upper spring cups were damaged, I needed 1 5/8" and could only find 1 7/8" spring cups. Amazingly, steel, small block Chevy freeze plugs were the exact size, so I welded the spring retainer from an over sized pair of cups on the freeze plugs, and put in a 7/8" hole. I think it might work. (even with my sh**ty welds)