The big block mopar is not a standard WOODRUFF key like you buy at the hardware store, it has extensions on it, like this one from summit.
https://www.summitracing.com/parts/mop-06509258aa?seid=srese2&utm_source=bing&utm_medium=cpc&utm_campaign=Brands+|+M&utm_term=4581802393709008&utm_content=GSAPI+5ba28999bb37f
Some, most before 1975 or so, RB and B Mopar V8 motors came with a standard key and some of the later ones had tips on them, not all of them came that way
Both work fine as long as they are installed correctly
