1960 Valiant Overcenter Spring and Clutch Questions

Ian, it looks like a spring was in the hole closest to the pedal side, you can see a small wear mark on one side. The 60-61 cars were quite different so I am guessing it had a slightly different set up. If a 62 up spring is close on length, could you drill a couple of holes to mount the spring hook?
Can't tell on the clutch builder, but I would think any 9.5 clutch assembly would replace the unit for stock use.