I have a 94 Roadmaster 5.7 LT1. I had a set of Bosch R6 plugs [HR8KII33V] but was never able to determine if they are for this engine. Have decided to go with ACDelco which lists 2 possible double platinum plugs, 46902 [gapped at .060]and 46906 [gapped at .050]. Any preference for one over the other?