[Excaliber]

Well that may answer a question I've been wondering about for some time. 'Rumor has it' there were TWO different high riser heads. That could be the late '63 referenced here, OR there appears to be both an F and a K high riser in '64? Two, possibly three different configurations for the high risers?

As far as I know Shelby never delivered a Cobra with high riser heads to any customers. As for the competition cars they very well could have run some, more likely they would have used the alloy heads which were rare but available to Shelby from Ford back then. You can bet some independants would have run the high riser heads. My heads came off a "T-Bolt" in Texas.

As for notching the cylinder bore at the top for valve clearance. Were ALL 427's notched or was that distinctive to a high riser block?