Hi Lofty, I think you would struggle fitting the action into anything other than a new custom made stock, as the breech block is uniquely shaped and curved. As you say, a lot of the rumours about reliability were related to very early examples (mostly press supplied guns). I know two other shooters with this rifle, none of us have any issues with them.
If I hadn't bought the Steyr roughly the same time as I bought the FTP, I would not be advertising it for sale. I have had many airguns (virtually all of the Daystates, from my current Regal to a Target). The FTP wipes the floor for build quality and accuracy with all of them.