... you took an old spark plug, drilled it out down the middle, attached a hose and a pressure gauge? would this be good enough for a compression meter?

Model, year?????

any model/year the spark plug fits?

Best method for doing that, is to bust the ceramic out of the base and weld/braize an air fitting to it. Then you put the chuck end on the gage using a length of hose. Now, you can either take a compression reading, or use it to put air in the cylinder to hold the valves closed when doing valve seals.

I wonder how many people are sitting there going "now THAT's a neat way to get NOS!" - until they realise that a cylinder ain't much use without a spark plug :D

or... you could just go to harbor freight and buy a $15 gauge.....

I could, but where's the fun in that?