As inexpensively and expertly as Oregon grinds camshafts, there's really no excuse not to go with one of their grinds for a slant six. They grind off factory cores they have, or you send. That way, you have the expertise of Ken and Bill, plus you don't have any of the worries of the Comp gear being too hard. Seems like a no brainer.
I don't know anything about the Erson cores or where they come from, but I've not heard anything bad happening with them.
I do hope with all the good advice here,
@Princess Valiant did not choose a Comp grind. Besides the gear problems, they are out and out slack *** grinds that suck hind tit. Just my personal opinion.
That said, I've always wanted to see what a solid version of the 340 grind would do in a slant six. It couldn't be ground on the factory 114 LSA, because the slant six cores are ground on a 109 LSA and they cannot move the LSA "that much" but they could get it on a 110 or a 108. I recommend sticking with low (under .500) lift to remain reliable, not require stupid high spring pressure, or expensive machining on the heads and expensive valve sprAngs.
Again, all just personal opinion.
