If you are interested in more detail about the use of the fixed PaK, I did a book in the Osprey Fortress series. If you are looking for modeling detail, I did an article in Military Modeling (Vol. 40 No. 4, 2010) on the 8.8cm Pak 43/4 that can be built using the Dragon kit. The model can be seen here in the gallery.
If you want to do more research on this, the Artillery and Fortifications discussion group on the Axis History Forum has a running discussion on the Sockellafette with a lot of photos:
If you're willing to spend more time digging, the German fortification journal published by Interfest has a good article by Herbert Jager "Leichte und mittlere Geschutze des Atlantikwalls" in volume 20 (2006) which contrary to the title, includes a number of pedestal guns used in the Rhine Pak Front including fairly simple drawings of some of them. This journal is fairly scarce but can probably be obtained from the publisher: www.interfest.de