Dragunov PSO-1M2 Scope

The scope is a 4x24.  It has English marking painted on in addition to Cryllic markings that are cast into the Magnesium parts.  This is a very light weight scope.
The reticule has black markings when viewed in daylight, but when it's dark the same markings take on the color of the lamp.

A friend wants to make the night illuminator operational.  There are problems:
1) the factory battery was missing and he replaced it with a Saft LS 14500 3.6 V Lithium (maybe Radio shack 230-0265) (Google search $5 ea) but I've read that the factory battery was a common AA 1.5 V.
2) the lamp is missing.  You can see the threaded hole in Fig. 5 above.
3) the battery cap (Fig. 4) is marked (-) ->, i.e. it's showing a polarity.  Is that because the lamp is an LED or because of mechanical reasons?

The factory battery was the common 1.5 V AA cell and I assume the factory lamp was a filament type.  There are many possible retrofit battery lamp combinations.
One of the common ones is to use the Saft LS 14500 3.6 V Lithium 3.6 V battery and an LED lamp.  These are available in red, green and yellow.
Another option is to use a common 1.5 V AA cell and a special red (only color) LED.  I don't see how this works, maybe a special LED or maybe a blocking oscillator to boost the 1.5 V.
The Duracell D357/D303 is mentioned on the Kalinka Optics (see below) page but they are 1.5 V Zinc air button cells and even when stacked would be much shorter than a AA cell so don't understand that.

Dragunov sniper rifle (WiKi)
Kalinka Optics - has a number of replacement lamps for the PSO-1 scope.
40 mm gernade
Dragunov.net - PSO-1 Manual has no info on the battery or lamp
AR15.com - PSO-1 manual - says common AA battery & no information about lamp
Снайперская винтовка Драгунова (СВД) -
kalashnikov.guns - 7.62-mm SVD DRAGUNOV SNIPER RIFLE - manual shows RC63 Mercruy battery & Lamp: CM 2.5-0.075 (maybe: 2.5 V @ 75 mA?)