A couple of years back I got on a kick and acquired and resealed, rebuilt several of the 747 and 777 Daisy types. The 777 is a much better built gun, having a all metal rear sight, and the notch width is adjustable. It also has a milled steel cocking lever vs the cast or stamped version on the 717 and 747. I think both the 747 and 777 have Lothar Walther barrels and both are quite accurate. The 777 with the big wood target grips and heavier steel parts makes it much heavier.
I also have a couple of the IZH pistols. Honestly it is easier to cock or charge with air due to the complex linkage of the piston, Sights are excellent and the trigger is absolutely out of this world. Mine are probably down to about two or three ounces. One of mine is an AV model that had the red black laminated grips, which I did not care for, and acutally starter splitting in a couple of places so I replaced them with some nice walnut grips from Rink. The other is a pure IZH with the beech grips that were rather blocky until I modified them to fit my hand. Now they fit, and look like a set of target grips instead of a block of lumber. Basically I created some finger grooves on the left side of the stock where my hand wraps around instead of having a square edge. I took the wood down over several weeks and stages until I got it to the point where I though no more removal of wood would help any, then smoothed and refinished with some tung oil.
If you want a pure target gun go with one of the IZH guns. I know parts are and may be a problem but then they are no longer replacement parts for the Daisy guns either. About the only thing you should need for either is O rings, and those are not impossible to find. I actually got some "kits" with polyurethane O rings for the Daisy's a couple of years ago off ebay, but no longer see the variety that was available. The ones I got used some split teflon washers or rings vs a foam wiper to hold oil for the cylinder, so no worries about foam breaking down., but again, I no longer see them available.
At my age both the 777 and IZH shoot better than I can.