How much can safely be milled of an intake manifold?

[Sleeper]

I'm working on a 4.1 stage motor and have Champion irons and Felpro 1000's on it.
Since the deck height is different between the stage 1 4.1 and the 3.8, ( I think it's .025) I see that the intake needs to drop a bit lower to fit.
How much can safely be taken off the intake?
How do I calculate the amount to take off?
You can kinda see in the pic where the intake bolt hole lines up with the head bolt hole.

 

[pacecarta]

you can get thinner (and thicker) intake gaskets from TA performance
they show an .016, .031, .047 ,.062 (close to stock)

 

[THensley]

More iron heads around than intakes I would cut the head

 

[THensley]

But I would try the thinner gasket first

 

[Sleeper]

you can get thinner (and thicker) intake gaskets from TA performance
they show an .016, .031, .047 ,.062 (close to stock)

Thanks.
I think my issue is that I went with thinner head gaskets Felpro 1000s (.039,) VS stock thickness (.063) Plus the different deck height between the 4.1 Stage and 3.8 (.025)
So options are, try to mill the intake to fit, or pull the heads and gaskets and go with Cometics, but need to figure out the thickness that I need to get proper manifold clearance.
Thoughts?

 

[Sleeper]

More iron heads around than intakes I would cut the head

They are Champion CNC Irons so don't. want to hurt them.

 

[Sleeper]

But I would try the thinner gasket first

I wrote an update and I think this is a head gasket thickness issue.