The rescue hoist was mounted above the right front seat and the rescue hatch below it so it had to be removed or folded forward for hoist operations:
There were several instrument panel arrangements. The top one was BuNo 128503-128600.
The cabin interior ended at the attachment point for the aft main landing gear strut;
The engine was mounted aft of the hole in the bottom of the fuselage and backwards, so the drive shaft pointed aft and the engine exhaust stack was forward of the engine.
The engine was mounted at an angle and drove a gearbox that had outputs forward to the front rotor and upwards to the aft rotor.
The above inboard profile appears to have an early version of the trailing edge of the fin. This fuselage stations drawing can't be strictly relied on for shape but the station dimensions should be accurate (the overall length of the "shadow" on the ground was 31' 11"):
Or a bit less as shown on this three view;
The HUP-3s were H-25s built under contract to the Army. Fifty were delivered to the Navy instead. The H-25s had a slightly different interior and a different rotor head; the Navy may have installed the HUP rotor heads at some point.
For an excellent review of the Amodel HUP kit, see http://alexsmodelling.blogspot.ru/2017/03/hup-retriever-amodel-kit-review.html