No, you need a 68 or newer flexplate on the 74 motor. This will be obvious if you try to use the wrong flexplate, it will not fit. But don't forget the bushing in the end of the crank, if you use the push button trans. This is not so obvious, as the trans and engine will bolt together without the bushing, but can have vibration problems, possible crack the flexplate, and/or ruin the trans pump bushing and/or seal.
All 60 to 67 slant six 904 flexplates are the same. All 68 to 87 slant six 904 flexplates are the same.