Engine/Transmission (1998.5 - 2002) Bigger cam causing problems?

[DPike]

On the 98. 5, I had to rebuild the motor at 215000 miles, because the tone ring on the crank came loose and broke the block. I got a machined block and all rebuild parts from Enterprise, and had my head redone at a reputable shop near me. At the time, I put in a LSM billet cam that a friend was running in another truck ('01). His has flycut pistons and heavier valve springs, but he also truck pulls with it up to 3200 rpm, and his motor was built for bigger mods in the future. A guy that used to work at eep said it should work fine in my motor with stock valve springs and pistons. The motor ran great for 25000 miles (i use it for towing) and then I noticed oil coming out of cyl 6 in the exhaust manifold. I pulled the valve cover, and nearly all the exhaust valve seals were messed up-still in place on the head, but the rubber was cut at the top, and some of the little steel springs on the seals were misplaced or off. Not knowing if the cam was too big or the head has issues on the piston side, I replaced all the valve seals with Cummins seals, and turned the motor over several times by hand before I put the valve cover back on. No problems. I towed for 40 miles, and had oil smoke out the exhaust again, so pulled the valve cover and already 4 or 5 exhaust valve seals are messed up the same way. Never ran the truck over 2400 rpm. I am thinking that the cam is too big, and either the retainers or keepers are hitting the rubber on the valve seals and ruining them. Anybody have experience with this or have any ideas? Just want to check before I go back to a stock cam. Thanks