I've used both the 260 and the 268 cams, and they're both good choices. The 260 works best in trailer-towing situations, while the 268 gives a little more scoot for passing, etc. The 268 has enough idle lope to declare "I've got a cam", while the 260 resembles a stock engine with a slight miss. Both work well with basically stock torque converters, but the 268 can benefit from a slightly increased stall speed.

Valve guides- - - - -The only problem happens when valve lift approaches .450" or more. Then the valve spring retainer squeezes the umbrella seal or positive stem seal, and might get metal-to-metal contact, which can bend pushrods. The fix is to shorten the top of the valve guide a little. The 260/268 cams don't have enough valve lift to be concerned about interference.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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