My guess is that the chain guide broke first and the interfernce of the pistons meeting the valves broke the cam. I would guess you'll need new valves. The pistons may be beat up pretty bad but you can see them when you pull the head. They (the pistons) will probably be ok but hopefully someone who has rebuilt an engine will chime in pretty quick and tell you how bad is too bad for them.

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1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k