Unless you're a good enough machinist to take some chunks of heat treated 6061 and whittle out new pieces from scratch, it seems like it would be a whole lot easier, cheaper, and more reliable to just have a cam ground to the specs you want end up with using the stock rockers, and not screw around with modifying them.
I have wondered how practical an idea it would be to redo the rocker shaft stands to accommodate some sort of high ratio V8 rockers and shafts, or if there's even room in the slant head for those kind of shenanigans, although I bet Madmax or Mr. Dutra have or would have gone down that road if it was viable.