If fuel economy is your goal, then a stock replacement cam would probably be best. Personally, I prefer hydraulic lifters. Much less maintenance. And the way I've cleaned the tops of pistons is with carb cleaner, a putty knife and lotsa elbow grease. Now if you're leaving the pistons in the holes while cleaning...well, I'd sure wanna run a shop vac around the edges just to make sure that no junk got down between the piston, cylinder wall and top ring.

hth,

Ray
Enter the Chevy Asylum
"The Ugly Truck"