The 235 mm x 70 mm x 110 mm is one catalogue
But Pertrix 85 is listed as 240 x 70 x x 110mm in Radiomuseum.org
241mm just fits the battery location.
Using full width of 750 gm Kellog's cornflake packet, I can make outer front, sides, top and bottom.
The image is then printed in parts on 90gm paper.
The rear (with MADE IN BRITAIN ) is printed and stuck on an inner rear tray holding
6 x D cells = 9V in a single 3 x 2 layout holder
60 x AA cells = 90V in six off 5 x 2 (10 cell) holders wired in series.
LT is a little over 50mA, so Zinc Carbide a little less than 100 hrs and Alkaline a little over 200 hours for LT D cells. Zinc Carbon F cells, if you could fit 6 in, would be just about 150 hours.
If HT is about 7mA, then Zinc Carbide AA about 130hrs and Alkaline 300 hours.
LT is more critical than HT, so I'd be inclined to use 6 x Alkaline D for LT and cheap Zinc Carbon AA for HT. Cheap PP3 would be about 60 hours for €15 at best, The Cheap ZnC AA are about €9 for maybe 120+ hours.
I didn't find "scans" or layouts of any of the packs listed. My B135 is faked by editing and scaling a B136 (As I did for the B137)