Vintage Seamaster Cosmic 135.017 spare parts

Hi guys, first post here on the forum. I'm quite excited because it means I got my first Omega watch: a manual-winding Seamaster Cosmic, reference 135.017 (or at least I think so, as the reference number is partially worn off).

Now, it clearly does have some aesthetic issues, but I still couldn't pass on it because of its stunning dial (at least to me). I got it for a fair price, and it's going to get serviced soon, as it's currently losing about 4 minutes a day and I'd like to avoid any major problems.

Movement-wise, it should be powered by the Cal. 601, but due to it being a front-loader, I'll only know for sure once it gets to my watchmaker. I'm aware I took a risk, but the price was really low, and I bought it from a guy I've purchased from many times before, and who never disappointed me.
Dial and hands seems ok to me, not repainted nor swapped. Case seems, at least to my untrained eye, unpolished (even if heavily worn on the inside). I hope you'll confirm that as I know almost nothing about this model or omegas in general.

I'm not planning on getting it re-plated; on the other hand, I would really love to track down original spare parts for the crystal and the crown. Does anybody happen to know what I should be searching for?
Should i get the hands lightly polished up?
Thank you all for your attention.
Luca

I really appreciate your response, even if that's not what i was hoping for. I did not want to make this about money, but I got it for less than what the loose movement goes for (still i'm assuming there's a 601 inside). Would you suggest to sell it for parts without wasting my time/money on it? I truly like it, and I would keep it for myself, but probably i'm over-estimating it's conditions.

Understood, thank you for your knowledge and all the infos about the spare parts.