The 261 cam has only slightly more duration and possibly a little more lift than the stock 235 cam. It would be a major step backward from what you have in there now, but it would definitely make it idle! In general, about 270 degrees of duration is the max I would reccomend for a street-driven cam. I'm not sure where the 261 cam comes in there, but since it was used in the heavy-duty trucks, it's more of a low-end pulling cam with lots of torque than something designed for high-RPM horsepower. Your compression increase with the decked block probably needs a little more radical cam than the 261 would be. Closing the intake valve too soon with high compression will cause some pretty severe detonation at times due to the fuel trying to self-ignite (diesel) due to compression pressure. A friend put some 11:1 pistons in a Triumph TR-4 engine with a stock cam, and promptly detonated holes in a couple of pistons.
Jerry
