Letterplate replacement problem

[Roland King]

The 12 inch outside letterplate on my uPVC door is very much in need of replacement (a Yale type now discontinued). Unfortunately there doesn’t seem to be much on the market for this type of product - a lot of it looks cheap and cheerful, and of course there’s nothing I can find with the same dimensions (the critical ones are 290 bolt centres and 273 x 47 aperture/cutout); the door thickness is 45 mm. I have come across the Regency DL107 BPB (Carlisle Brass) that does have the same bolt centres and is of similar other dimensions. Although this is intended for a wooden door I wondered if it might be possible to use it with the existing telescopic sleeve setup. Other than that there doesn't seem to be anything else available. One stockist offers a "massive range" of uPVC door letterplates - this turns out to be 6 items of which 3 are out of stock! Has anyone encountered this problem before or got any guidance to offer?