'64 Mk2 3.4 Girling brake servo question

Hi Guys, I hope you are all well in these difficult times.
I have a 7" Girling brake servo which I want to completely recondition.
My problem is I can not find any of the usual’s selling a complete kit to suit. Even tried Ebay. Anyone buy a full kit lately and from where ? The kit(s) number would also be a good help so I could do an online search for it. Would prefer to buy a complete kit as opposed to component kits which on their own seem to have dried up as well.
I have not yet stripped my servo but anticipate the cylinder will need resleeving, been sitting for a full 20 years.Should I be considering stainless steel sleeve? Has anyone been down that road with words of wisdom from their experience?
Thanks in advance

Just for comparison here are two servos, one from my 1965 3.8S that is original and one similar to what my shop recently installed when they discovered a small vacuum leak in the 55 years it has been in the car. I think the one on the left is a Girling and the one on the right the original from the car, (a Lockheed?)![Brake boosters . The Girling ones are relatively commonly available as replacements, the other ones not so much. I have had master cylinders and wheel cylinder for cars sleeved in stainless with considerable success over the years.

Eugene try/google past parts. Also try http://www.classiccar-brakes.co.uk/contactus.htm, and lastly JLspares.

I’ve used JL spares in the past and have been impressed

past parts co can be expensive

Thanks guys for the replies. My servo is an original as on the right of Johns photo.
Phil I shall phone around on Monday in the hope some of your suggested vendors can help.