The Pinside price seems a little high to me. Boston Pinball Ebay guide shows an average of around $400. In my opinion, old classic games in this very low price bracket don't flex much with repro parts - a nice glass, repro or original, is a simply a nice glass and that is desirable. As long as the repro is of high quality, it shouldn't have much bearing on the overall price, unless a buyer is totally opposed to repro glass.

I would price the game as a whole all things considered, and just list in ad descriptions and inform interested buyers of any repro parts on the game. If someone wants a percentage off, then you'll have to make the decision at the time if that is in your best interests.

That's a nice wedge head machine for a decent price as it sits I think.

The basic subtext of your question seems to be why are pinball games not priced like they would be if the buyer was a museum where only original pristine is of value. The answer is they are but that procing only holds for pristine original games. All the rest- 99% of them, are purchased based upon these two things- a solid playing game that looks great.

If you have a PRISTiNE original then yes a repro probably devalues it if you pull out the perfect original glass and replace it. If you have a game with a crap glass I think the repro increases its value.

There is a only one simple question based on your initial inquiry.
"What is the quality of the reproduction backglass?"
Tempered ink screening, modern heat sealed laminate glass, plexiglass screen, poly print, adhesive transfer, paper?
There are many more types of image creation, I could list.
Even between producers of ink screened backglasses there are differences in quality, some good, some poor.
Shay Group BGs in general are better quality for example than CPR, as too many liberties are taken with the artwork change.

Ron Webb makes quality reproductions, not poor examples.
He has made backglasses for over 25+ years (privately, at minimum, before even providing to the public).
Equal or greater than an original quality unless it is a NOS factory glass, increases the game value as one of the primary "big four" areas of consideration.

Playfield, backglass, mechanics, cabinet in this direct, specific evaluation order regarding electromechanical games.
SS games are a bit different as the order is prioritized as playfield, mechanics, backglass (many times translite, unless missing), electronics, and cabinet .
This SS change is due to the increase in complicated assemblies with hard to find parts, although there are some exceptions to this rule such as Bally's Nip-It 'Ballgator' assembly.

You also need to look at the collectibility of the title itself in order to determine final pricing, as one area cannot be exclusively determinate for value.

One area that is constantly misunderstood (especially presently based on new hobbyists) and was not mentioned is EM cabinets. Restenciling cabinets, especially improperly with incorrect factory pantone colors and speckling actually DECREASES value dramatically for games. People need to leave cabinets (and badly touching up backglasses) alone to avoid the "kindergarten crayon" effect, if not familiar with proper techniques.

You can PM me for photos regarding the game evaluation, as I do not provide price value appraisals on this forum.
I speak from the experience of developing my own screening films including required vectoring and reproductions of backglasses, and many other areas of restoration.

Keep flipping.