Twostick makes a good point in that today's crap gas with the best premium blends are not the equal to yesterdays fuels. Unless you are planning to run some Sunoco 360 with you premium pump gas, you probably do not want to go much over 9.5 on the compression ratio. I find that running the Real Gas premium I can get away with a 10-1 ratio and it runs fine, but at about $5 a gallon if any significant miles are to be put on the car, that makes for some fairly expensive driving on a 10-12mpg car. The '67 516 head was to designed to run at 10-1 with 100 octane fuel using the old measuring system. You can compensate for today's crap gas some by fiddling with the timing, advance curve and carb metering and that can take some time. The choice for you would be if you are looking to avoid all of the fiddling, then calculate a 9.5 comp ratio and figure out which gasket will get you there. With the shim gasket you will probably be running a solid 10-1 and your timing, advance and metering are all going to have to be spot on to get it to run right.
Dave