wuzak
Captain
It was more like two birds in the hand being worth more than one in the bush. Would the Chrysler engine increase the power of an R-2800? A Packard or Ford Griffon would have been installable in a Mustang.
There is a reason why the Griffon Mustang never proceeded.
There were quite a number of changes to the airframe in order to fit the 2 stage Merlin, including moving the position of the wing. Installing the Griffon would have required even more changes.