So what is the big block choice of plugs nowadays?
probably the autolite 85 or the ngk thing. rj12y's aren't very good. not sure AC numbers would work but just make sure you use a projected tip. i really don't buy anything buy brand name exclusively anymore. and sure don't follow the internet/magazine herd. i just look for what fits my needs and works and forget about names on the part.
Becareful with the Autolite 85, new isn't the same as old ... that was my go to plug for a while ... when they moved production to Mexico years ago the quality went to poo poo , electrodes offset in the porcelain.
Mark I'd look at the NGK listed in the photo Nick posed , XR4 , or go on fleabay and find a set of the Mopar branded NOS plugs 34P , P34P , they are the J-11Y equivalent.