Checking head thickness to confirm machine shop work?

[jag240sr20]

I took my head to the machine shop the other day to get it resurfaced. When i picked it up today he told me he had to take off 18 hundredths (.18") to get it straight but im thinking he ment to say 18 thousandths (.018") because .18" comes out to like 4.5 mm which is rediculous. Is there a way i can check the head to confirm how much was actually taken off?

[OM3GA]

Measure it from top to bottom on the side to check its thickness using something accurate like a digital calibration device.

And if it were 4.5mm taken off you would definitely see the difference.