Refurb help

I have a TAG Heuer 980.031L, which I purchased new in the 80's. Other than a couple battery changes, it has never been refurbished. The crystal is badly scratched and I assume all the gaskets need replacing. Am I correct that this takes a 27.5 x 2.5mm crystal? I will get a generic sapphire off eBay but want to order the right one. Do I need to track down an L-form gasket for the crystal? What o-rings do I need? Assuming I get all the parts, is this something a local watch shop can handle? The black on the steel band clasp has worn away to raw steel. Leave it as is or is there something to re-black it that will look nice? Thanks!

Very nice watch, which has to be treated accordingly.
Parts are not that expensive, but the problem is that most of them are obsolete now...so you really need someone who knows what he is doing.
Just buying parts from the net and then dump it all at a local watch shop who can sort things out for you is waiting for a disaster in the making though, both technically and economically.
See if you can find a Heuer/ TAG Heuer/ 1000 specialist in your neighbourhood would be my advice.
And the black PVD can be replaced, but is a very time consuming and expensive job to do.

The PVD is hard to refinish on a case..and almost impossible for the bracelet. You'd have to first strip back the old PVD before applying the old, which is tough on those jubilee bracelets

Exactly as Calibre11 says, see here an example of a "refinished" bracelet from black pvd to grey that I have overhere.
Not nice.

Is that pitting caused by the bead-blasting?

I am not sure as I bought it in this "refinished" condition, but it certainly looks that it has been bead- or sandblasted before they put "a" coating on it.
I threw it straight into the parts bin after I received it though, haha, too ugly.
I have read years ago that the best way to refinish a PVD coating is polishing off all the old coating and then put new coating on it, whether or not with a primer... but may be there is a better technique to do this?