Remove a few springs and check them for load on the seat and open pressure. The mp cam doesn't need a monster spring,but there is no way I'd trust my luck with very old springs. I just went through this with a friend. I built him a SB for street/strip use 12 years ago. He calls to tell me that it's lost mph and rpms. The old springs were very tired and likely were worn out years ago.On the positive he's won enough money over the years that new springs didn't hurt the wallet much.