Happy New Year, Dennis.
In looking at your pictures, I understand what is causing you to raise the question. Much depends on whether the heads you have are posted or not.
Click on the link below for the information provided by Tim McMaster to determine whether your heads are posted or not . . .
http://yblockguy.com/techtips/postedheads.htmlAfter determining whether your heads are posted or not, you need to use a micrometer or micrometer caliper to measure the thickness of the 'pads' located on the exhaust manifold side of the heads. The pads are located at the front and rear corners of each head and below where the exhaust ports exit the cylinder heads and adjacent to where the spark plug holes are located. The thickness dimension of the pads between their top exterior surface and the surface that mates with the engine block deck was 1.000 inches when they were originally manufactured in the 1957 or the 1958 vehicle production year. Subtract your thickness reading from the 1.000 dimension to determine how much your heads have been cut AND whether the two were cut equally.
Check to determine IF the pads measure the same thickness on the front and rear pads on each head. IF the pad thicknesses vary significantly from front to rear on each head, it will indicate how they were machined OR how they were set-up by a shop that resurfaced them. Too, IF the pad thickness is different between the two cylinder heads, you'll know that the machine shop that did the resurfacing did not cut them equally and was likely looking to simply clean them up enough to ensure that they would seal uniformly against head gaskets.
John Mummert recommends that un-posted y-block Ford heads be milled a maximum of .025 inch. This machining dimension is recommended to prevent the cylinder head deck surface from flexing in service and causing head gasket leakage.
On his web site, John Mummert reports that posted y-block Ford heads have been milled as much as .045 inch without problems when put into service.
In rebuilding an engine for Karol Miller, Ted Eaton reported that he re-installed a set of 5752-113 heads that Karol had been running that had been milled .080 inch.
Click the link below for Ted's report of the Karol Miller engine build . . .
http://www.eatonbalancing.com/2015/05/01/unported-iron-heads-can-still-make-over-a-hp-to-the-cubic-inch/Click the link below to see JM's cylinder head info that I've referenced above . . .
http://www.ford-y-block.com/cylinderheadchart.htmHope this info. helps! Enjoy your summer!
NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York