Perfect intake centerline

You mean when the intake opens? Or cam centerline like a 110 and the intake is on a 106 and should it be moved to 104?

It's based on a few factors. Cube size, cam profile and performance goal.

A 110 is a typical centerline of a performance cam. I would prefur a 108 on my 360 and have had it down at 106. The idle gets ruffer the lower it goes. But this also is part of the cams profile.

I like a 112 to 110 for a 318
110-108 for the 340 and 360 for general performance up to a preety stout engine.
Minus 2* for a race engine and up to 4* for a all out engine.

Alot of this topic is realy tasters choice.