Oof. Excellent stuff and a really good find, Dave. I actually saw it on that sales site last night and noted its location. It fell perfectly for you in the valleys there! Looks like I'm on here before Geezer so here goes:
34 introduced March '84 but Im not sure when the first of them landed here as Originals. So you have the earliest incarnation of the model with the non adjustable trigger. They are referred to, unofficially, as short tube with 28x77mm bore/stroke which may mirror or at least be very close to the O45 and FWB Sports. Very plain and simplified construction as you say but well built and finished. The short dovetails are best suited to two piece mounts as I think the vast majority of one piece will be too long.
The point of the 34 was to make a simplified, no frills, full power gun that was cheaper to produce than the 35 and 45 that could be offered at a lower price point. Interesting to note that Diana started to develop it very soon after introduction with fitting the revised 3 ball trigger, sight ramp before introducing the fancier 36/38 and more deluxe 34's later. Id say your 34 would be considered a more powerful competitor to an HW50 or possibly a HW35, although I think the 34 needed its 3 ball sear trigger to compete with that gun. Comparisons with an HW80 would be better left to the 36 or 38 with their better triggers, sights, stocks and cast fittings. By the way if you're not too enamoured with the 34 and would rather have an 80/85 I'll send one down tomorrow, cash/whisky either way.