That is all true but you have a bigger problem due to the 15 degree valve angle. So your rocker shaft height is limited by the length of the rocker arms. That is why you have to ignore the math and just put the rocker arms where they work. Only exception to this is if you're starting with a clean sheet of paper and are designing your own setup. Then you can control the length of the rocker arme and therefore the location of the shaft.
Ignore the math, and put the rockers where they work. The ultimate oxymoron. The math IS putting the rockers where they work. Accounting for the valve angle is just a part of that math. What do the Small Block Chevy guys do when running longer valves and a stud mount rocker. They have a 23 degree valve angle which causes more of a problem than a 15 degree angle does. Well, they use rockers with an offset trunnion to move the rocker away from the valve centerline, and restore the rocker tip to valve tip relationship, or they have to offset the stud holes in the head. When they use a shaft mount system, the stands have an offset designed into them that accomplishes the same thing. They still have to make sure the shafts are at the right height, and some "one size fits all" stand height tool isn't going to cut it. Mopar guys aren't the only ones who have to do a lot of extra work to make geometry correct.
If you have the stands milled off already, you can move the shafts wherever you want. Knowing where "wherever" is, is what's important.
