Tommy Torres

James, I'm new to the board, but will provide you with another possibility, first anytime you have coolant and oil mix together it will require a very extensive cleaning of the internals to remove the sludge the mixture creates. That stuff is a pain to completely get out of all the oil galleries and lubrication components, so yes some can be residual, but it is important you get it all out so as not to damage extend the damage to the internals such as the crank and rod bearings. Once that's done all parts should be closely inspected for any signs of sealing surface damage, warping or cracks on the parts. It may be the cylinder jug has a hair line crack which you may not have been able to see, but when you got the engine back together and ran it, the heat caused the crack to expand and allow coolant into the engine block. I would recommend you conduct a cylinder leak down test, this test will not only show you the condition of the cylinder, piston and valve train sealing surfaces but will allow you to remove the radiator cap and look for any air bubbles which is a sure indicator of a problem in the cylinder. Another option is to replace the cylinder jug and head assembly and gaskets with new ones or obtain salvaged but serviceable replacement parts. Hope this is helpful