I am building a 383 and when I put the distributor in it’s not going all the way down. I pulled the oil pump drive out and the tang on the distributor shaft is too wide go all the way in the oil pump drive. I am using a MSD pro billet distributor and the oil pump drive shaft came from 440 source. I also tried a stock distributor and it is too wide to go in as well. Should the distributor be able to go all the way to the bottom of the groove in the oil pump drive?