911 SC AC rotolock o ring question

[avr924]

Ive had my 911 for 14 years, and despite living in Houston, TX have never put any time into getting my a/c going. Now that Im older and wiser Id like to experience driving the car year round in comfort

Before taking the system fully apart I was surprised to find it holds a vacuum very well. I believe part of my issue is sealing the rotolock bolt-on flanges on the back of the A/C compressor. Also fair to assume I may have some leakage through the hoses which all look to be fairly original to the car. No drastic leaks fro what I can tell.

A couple of questions:

-Does this roto-lock assembly have any other seals besides the square cut o-ring that fits in the groove pictured? Ive seen various other rotolock assemblies with Teflon o rings, and a gasket to seal the entire rotolock assembly to the flange.

-Assuming this o ring is all that's needed, any good sources for this square cut o ring or does anyone have dimensions? I can measure the groove but assume there is some clearance required in there for the ring to compress once tightened up.

As a note, a Griffiths full system is on my wish list, but want to try to at least get the current system going at the moment. Thanks for any help and insight!