The test is to get the correct head gasket thickness to maximize compression while avoiding any chance of piston valve or head contact, or even over compression, that's why they have different options of gasket. Its one of these things that is best to have right and may or may not be part of your previous problems but when you do something like this its good to know all of it has been done right, given the cost of the gasket, the new stretch bolts, even the sealant between the head and the cam shaft retainer is expensive.
It may just prove you have the correct gasket anyway which then eliminates something from the list.