If you're going to go 60mm without shocks to match, they won't last long at all, the rod will be sat permanently too low in the cylinder. The gas will escape due to the pressure.
If you can deal with the ride though, corners seem a lot more fun afterwards.
I have 50mm on both of my cars with 15's, and the handling is awesome. The red one has decent dampers, and the difference in ride and handling is very noticable.
"C20 LET bang"