fattest cam in a 340?

take your valve cover off on #1 cyl bank, rotate clockwise until #1 intake valve is just closing ,STOP look at damper and find timing mark,.measure from mark to zero on timing tab. record measurement.continue rotating clockwise until intake valve is just closed,
again measure from mark to tab, note if it is before or after 0 mark.
let me know what you find then I will help you with the next step. good luck