W2 heads I think they are ready

12 swinger
SURPRISE!!!
better now than later

IMHO Crane and their Quick Lift theory suck or as some say Quick Lift was a cover up of their wrong early lifter designs
somewhere the adjuster length got changed and they just kept selling rockers
lots or rockers have the adjusters NOT in line with the pushrod at half lift- puts a strain on the adjusters, cups hit, etc
btw the measurement from the bottom of the rocker to the bottom of the ball is for stock Iron rockers
Aluminum can be thicker or angled different and are all over the place
just the balls as high as you can without hitting , or notch some and go higher
of course the cup adjusters allow longer pushrods
do all this before drilling your holes