Keep on the Borderlands Question

Here's a question for you KEEP ON THE BORDERLANDS Fanatics. I'm contemplating taking on the great task of making a scale model of the keep ( if anyone has looked at my Blog you know I have started making lots and lots of dungeon sets from Hirst Arts). The whole model will be in sections to have access into various areas of the keep and will be about 4ft by 6ft in dimension ( I'm not sure about height since I haven't factored in if I want to build the rock plateau its built upon or not). I googled the keep and it seems no one has taken on this task so Id like to be the first. I think it would take me maybe a year to build it in my workshop  in my off time. I want to add as many of the elements listed in B2 as possible.

So here is my dilemma from a planing and building perspective. The plans of the keep show the back  northern towers - The Great Towers ( labeled 23 on the map) to be round towers and the eastern Guard Tower ( labeled 20 on the map) to be partial hexagon.  BUT- the artist picture on the back shows the Great Towers  and the Guard Tower to be square.  SO.... Do I design the Keep with the plans given in the module or go by the iconic artwork provided on the back of the module. I know this may be a minor discrepancy but as a builder myself, these things bug me.

So what are peoples feelings about which they feel I should use as my basis for my model?