I checked out your pictures then googled "David Gilmour's signature" (I'd paste it here but the url is massive). To my untrained eye your signatures look authentic, but that's not going to raise the value of your album.
Most of the webpage is pictures of David's Signature Stratocaster but there are quite a few pictures of
David's and Roger's signatures as well.
I would post a question in the Analog forum about how to determine if the pressing is a valuable one.