If you are using 1.6 rockers you'll most likely have to open the pushrods tunnels up. That's just what happens when we take stuff designed in 1962ish and modify the crap out of it.
Don't know about the valve seat issue? What's that about??
The shop that did my motor doesn't even want to talk to me about overseas heads LOL the other local shop said something right away about them not having good valve seats or something...
I think it includes pretty much what you're saying I mean once you modify the crap out of them all bets are off....