Rocker arms for 408 build

If Chevy/Ford rockers work for the magnum application why arent they available packaged up with the proper components by anyone ? Seems they would sell like hot cakes !
I’m pretty sure you have to piece it together still as I did a few years ago. Readily available Comp Cams has the exact studs and correct guideplates that fit the Magnum or EQ heads. You order custom length pushrods compatible with guideplate use. Crane looks too also offer specific pieces but the guideplate setup looks more complicated so as to be able to use regular pushrods vs. using “guideplate compatible pushrods” and simple guide plates such as from Comp. Could probably use Isky adjustable guideplates, but Comp will likely be at a much better price than any others for same quality. That’s why I went with all Comp, best value and readily available. Here’s some Crane listings:

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