Hello Sir,
I purchased Coker's Mopar14x6 Silver Rallye wheel (4.0" B.S.) P/N MRYS146 in 2019. I have them with Goodyear E70x14s on my '70 Duster 340 with factory front disc brakes and they work fine. Below is Coker's item description. The only thing I can think is perhaps Coker is referring only to the Valiant...i.e. the small bolt pattern was used on Valiants without disc brakes. Perhaps the '63 to '72 Valiants did not have factory disc brakes.(???) All I do know, these wheels fit front disc brakes on a '70 Duster.
Coker's item description: This silver powder coated 14x6 inch Mopar Rallye wheel is a great choice for your Mopar using the small 5x4 inch bolt pattern. The small pattern was used on 1963 to 1972 Dodge Dart, Demon and Swinger as well as 1963 to 1972 Plymouth Barracuda, 'Cuda, Duster and Valiant without disc brakes. It was also used on 1971 to 1975 Plymouth Valiant, Duster and Scamp with drum brakes. These premium wheels are made in the USA.
Hope this helps! Ed