So does the Panzertracts book on the Panther F and Panther II mention anything about a proposed hull and turret combination?

The Panther II project was canceled before a turret design was finalized. While it was supposed to be similar to the "F" Schmalturm, it was to be more heavily armoured in the front. To my knowledge there are no drawings of the Panther II turret, never mind a prototype mock up. Several elements of the Panther II design were rolled into the "G" for its production.

It's the F turret that most likely evolved from the Panther II one, of which a redrawn schematic can be seen in Panzer Tracts 5-4, when being handled between tank manufacturing companies. This model is the fake that was born from a misdated front report by Spielberg, later rectified. The Schmalturm and 88 kwk43 never were men at for the Panther II, but the myth struck and this model answers the "what if it did" question. But it's still not historical, as can be read in Panzer Tracts 5-4.

I think the schmaltrum was a liter development. Panther ii turret was similar in size and construction to regular large panther turret. The main difference is it uses a small pigsnout mantlet instead of regular panther's half round mantlet, and it had a low profile copula.

So is this a Paper Panzer or a wishful thinking?

It's Amusing Hobby so it's wishful thinking.

It's not complete paper or wishful thinking. The actually panther ii prototype is in running condition in Fort Knox. However to get that way it had to use a panther G turret, and a tiger II engine.

The engine used on the Ft. Know prototype is out of a Panther Ausf G. And turret is pure conjecture. So this ranks with their Jagdpanther II, fantasy IMO.

Their other model mentioned in the news is the actual proposed vehicle, this is a post war mistaken hypothesis. Also the existing hull is not anymore a Fort Knox since a few years, it got moved to Fort Benning, and although it technically is in running conditions, after a few breakdowns it was decided to not utilize it anymore due to the extreme rarity of the components, unique to it.