To change the cam, you must remove the rocker covers and intake manifold, then the lifters & pushrods; inside, pull the upholstered firewall cover & the steel firewall access cover. Then, pull the water pump, the harmonic balencer and the unique front cover on the 351C. The cam is under two bolts holding a retainer plate. 100% of these parts are accessible with the engine firmly bolted in place, and its been done multiple times as described. At least some of it can be done sitting in the seat....