they look like magnum head seals to me. Now, how many magnums do you see smoking at stop lights or at start ups after visiting Walmart? Ummmm ... zero. How many LA's do you see smok'n at start up because the valve seals are in the oil pick up tube? LOL.......
As far as shiming, height, yeah, more precise the better. Necessary? Naw. Think mother mopar did this in depth scrutiny to every X head on every 340? Nope! And we love those X-head 340's right from the factory. Again, like I posted early on, I'm not bashing ANY machinist.