Personal experience beats a WAG every time. Paint, even Glyptal transformer dope, DOES NOT adhere to the valve valley and crankcase well, at least on a couple of dozen small block Chevy racing engines we tinkered with. The only way we could ever get Glyptal to stick was to take an abrasive cartridge roll to all the exposed cast iron we wanted to paint and smooth out the rough casting surfaces. Then after a good wash-down with lacquer thinner, the stuff would stay put. The only good reason for painting inside a block is to keep imbedded sand from the casting process from washing off and contaminating the oil. On a street machine, it's a waste of time and effort.
Jerry
