Fantastic progress Wayne. I did a search and the Leo 451 was powered by the Gnome-Rhone 14N 14-cylinder two-row radial engine. Looking at photos on the internet the exhaust stains seem to appear around the engine behind the cowls. This would indicate that the engines on the LeO 451 possibly consisted of independant exhaust stacks for each bank of cylinders. Best seen on the profiles on these pages: WINGS PALETTE - Liore et Olivier LeO 45/451 - Germany (Nazi) WINGS PALETTE - Liore et Olivier LeO 45/451 - France
As far as the gun, it does look out of place a bit.
I looked at some Lioré-et-Olivier LeO 45 pictures on t'interweb and they give the impression that the main assembly of the gun was further in the cockpit area and the barrel lay flat on the fuselage when not in use.
At the end of the day though it's a plane and i know diddly-squat about them and any of the varients.
i thought i had written about this build(but you know what thought did?lol)personally i love this quirky plane,and the big gun well i think its great,what with necessity and all that,(throw on a big gun that should keep the enemy off),thats a magnificent paint job and excellent build