Are the lifters hydraulic? (probably, but let's not A S S ume anything!) Start out by doing a proper valve adjustment, where each lifter is preloaded 3/4-1 turn after removing any slack in the valvetrain with the piston at top dead center. Do a search on the forum for my "companion cylinder" valve adjustment method- - - -it works on all engines, 6 or V8, solid or hydraulic lifters. It's the most accurate way I know of to establish when a cylinder is on TDC and ready for a valve adjustment.
Once you're sure all the valves are adjusted properly, run the engine up to normal operating temperature. set the RPM at about 2,000-2,500 wit the idle speed screw, and slowly dribble a Coke bottle full of hot water down the carburetor throat. The carbon buildup in the combustion chambers will be steam-cleaned away by the water as it hits the burning fuel and flash-evaporates, and there is virtually no way to do any engine damage unless you dump a huge shot of water in all at once.
Jerry
