Let’s nail down some important details here!
If you do Mill off .070” then you have lost that same amount of piston to valve clearance.
Do you have that to play with now, or in the future if you ever go with a greater lift cam , or higher lift rockers?
Since it sounds like your working with the -8 heads they have a bigger combustion chamber in terms of width then the -4 heads.
This means that per every .006” wacked off the deck you are removing 1.2 CCs of volume.
This means that instead of a mill of ,045” taking off 7.5 CCs you are removing 9 CCs.
Since your heads heads are apart for the milling work and it sounds like your fighting for every reduction in CCs you can get I would step up to 1.77” exh valves which can be set in the chamber proud and pick you up 1.5 CCs almost.
Whatever amount you do Mill the heads do not give a potential crack any place to start so be sure to break / roll over all the sharp edges on the deck.
Be sure when you do that roll over work around the chamber that you do not undermine the combustion chamber fire ring of the head gasket.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!
1) 1940s 100% silver 4 cup tea server set.
Two dry rotted 14 x 10 Micky Thompson slicks.
1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.
Education is what your left with once you forget things!
Last edited by steve25; 12-23-2021 at 08:01 AM.
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