Help: Is this a good first Omega?

I am looking to buy my first vintage watch. I saw this listing for a 1970 Omega Geneve Ref.135.041 that is listed for a very good price, which the seller claims is because the crystal does not have the omega marking. It is listed on Chrono24 from a private seller based out of Vietnam. Aside from the crystal does the rest look authentic, and does it matter much that the crystal is not an Omega crystal? Overall, is it a good buy for the price?

Link: Omega Genève 135.041 manual wind for $300 for sale from a Private Seller on Chrono24

Ref.135.041
Cal.601
Diameter 35mm
Thickness: 9mm
Arm circumference: Leather belt
Band width: 18mm
Power reserve: Currently about 31 hours
Drive system: Manual winding

The crystal is not important. It can be replaced at a later stage and the only visible difference will be the small logo in the center. No big deal.

The crown looks like a replacement. Should be different for this reference and should have the Omega logo.

The condition overall looks good, but not pristine.

As said above, be careful especially buying from Vietnam (seller reviews? import duties?). You can always ask for more pictures and the watch to be set on a specific time if you want to ensure they actually have it and pictures aren’t stolen.

It’s an entry level piece, so prices shouldn’t be too high. You will probably have to service as well, so factor in another 200€ for this.