If a decent worker came up on eBay, I reckon that £700 or so would secure it. There are very few buyers for games of this era - pre speech, chiming, single ball, Bally first generation SS titles
A decent working Strikes and Spares (same generation game) went unsold for a while in 2018 for 750. I negotiated to buy it for 550, as I knew that it would be difficult to sell on when I was bored with it. The seller then backed out.
In your shoes, I would play the long game.