I’m not sure what the acceptable voltage range is for this motor
Moving right along, now we have a photo, I note the power block has skates (sliding pickups.) That means it’s a conventional G-scale power brick - it may have “Piko” or “Lehmann” or even “Bachmann” written on it. And it also means that it can handle at least 14-16V and maybe more. So four of those big batteries will drive it quite nicely. (It actually looks like the USA Trains power block I have in my Banta boxcab.)
The 4 wires from the power block are 2 pickups and 2 to the motor. They are not connected, so if you put the block on a powered track nothing will happen. If you want to test it, connect the wires together - the red/blue are pickups I think. (Check with a meter.)
I loved the 11,000 mWh on your battery. Most vendors use mah, so dividing the watts by the volts we get about 3,000 mah - fairly decent. You did say you were planning on squeezing 4 under the hood? Should fit, but you’ll have to take them out to charge them. They will last a long time so I wouldn’t worry about that now - just make sure you can get them out and they won’t touch each other’s ends. However, I see no provision for connecting to the top and bottom of the batteries. You really want all 4 in series to give you 14.4V.
And that raises another question that I can’t answer from the pic. Do those batteries have ‘protection’ circuits built in? I imagine they do, due to the micro-usb. Assuming the usb connector is a protection board as well, you are all set.
Aha. I found EBL’s website and note you are safe:
Built-in integrated safety circuit protects the battery from over-charge, over-discharge, short-circuit, and over-heat ensures complete safety for the battery charging.
What I do with mine is fit the batteries in a holder. This is a 4-slot and it has a protection board on top (you don’t need that as each EBL battery is protected) :
I also have 2-slot or 1 slot holders that can be fitted in odd spaces, like your loco hood! Here’s a bunch in a small boxcab: