Mopar Stage VI 6 heads questions

Ok I understand that I could use a longer length valve, if I do that do I need to use a spacer under the rockers?

Thanks
I hate to sound like a dick & I don’t want to come off as one, but here but here we go…..

Your 1st question was very general, general answers given.
Your second question was a little more focused but it’s still in a wide open field. So I explained it.

Your third question is more focused but still in a big field.
I’ll answer it in a second. First! What are you planning on doing with the heads?
Will your application need standard length valves or longer valves? What length do they need to be or will be?

Moving the rockers upwards is easy. Moving them front to back, (towards the valley or towards the exhaust side) or whatever is harder. This maybe needed depending on your valve lift, spring height and ultimate goal. We have no idea of what that is.
I do realize you’re looking for information and I’m happy to answer what I know. Which isn’t a heck of a lot on these heads.

Keep asking questions!

The suggestion to take to a head guy/machinist is an excellent one. What you could do is get to stock valves and used springs and a valve seal, etc…. Set up 1 valve and check it with a mic. This you could do at home if you have a mic and such tools.

Do you have experience worked by on cylinder heads at all, as in setting them up?