426 Wedge 1964 compression ratio

[Duster Wedge]

I have a 426 wedge engine that I am trying to figure out what compression it is.It is a 1964 wedge bored 060 over with stock stroke and domed pistons
the ID plate is stamped HP S is this engine 13 :1 ?
I need help figuring this out as it will be run on the street and an occasional run at the track.
It is in a 75 Duster that weighs 2,900 lbs
Can I put the 060 shim under the head and get the compression down to where I can use pump gas in it ?
What does the S stand for I know its a special engine but what's special about it ?
Any help you can give this old street rodder will be appreciated.

[mopar7172]

It's a street wedge