Thanks for the reply.
I'm not changing the cam (still using the Mopar 509). I'm considering to change from the stock 906 head to an aluminum head like the Edelbrock Performer.

Questions:
1.) If I just change out the heads, what is the suggested rocker assembly to go with ?

2.) Since the Edelbrock heads claim to be bolt-on, does that mean that I can use my existing PR as long as I don't change my cam ?

--> By the way....aren't all heads "bolt-on" ?

I understand your point about the height of the heads determining the length of your PR, guess I need to call Edelbrock to see if they are different.

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What is the engine used for street street/strip..
but a lot of guys like Harlan Sharp rockers but you might
be able to get away with a bit less... but my opinion
on rockers and valve train parts is to buy good ones
the first time so you arent replacing them later..
also I was thinking you were gonna change cams to
the 528 like Andy said... if the shafts are on the
same height as the stock head then with the adjustable
rockers you should be ok... if things werent cut
(like the heads)... also.. like was said.. the parts
on most of the heads and the valve job arent the
best.. I touch up the valve job on ANY new head that
comes assembled
EDIT
and no... not all heads are bolt on... some need
massive work