Seems to me just happenstance that the engines were Ford in original Cobras. CS would have been just as happy and likely as successful to use any of the american V-8s... So I would modify your above statement: "This forum would not exist if Carroll Shelby did not stick a big Ford motor in an AC and I doubt anyone would be replicating the AC Ace." to read "This forum would not exist if Carroll Shelby did not stick a big american V-8 in an AC and I doubt anyone would be replicating the AC Ace." Reads the same, except does not require the "blue oval magic". Certainly nothing magic about a side-oiler...
But CS did use a side-oiler and certainly with no regrets. So be it, however misguided he may have been
. However, if you are not using a side-oilerin your "replica", why would an incorrect Ford W engine be better than an incorrect chevy engine? Wrong is wrong, right?