You mean the first option in the TX Module list?
"4 - OpenLRSngTX by Kha"
That's not the right option for the Orange module, that's the firmware for Kha's new improved 1W TX module:
https://github.com/openLRSng/openLRSngTX
So you're actually loading firmware for a different module when you do that. It shouldn't hurt anything but since some things on the board are slightly different it won't work right either. So that's why you're not having any luck with that option.
For the OrangeRX TX module you want "2 - Hobbyking OrangeRx UHF TX" which you seem to be referring to as the stock firmware - but it's actually the latest version 3.4.0 of ng compiled for the OrangeRX module.
It's a little confusing and took me a few minutes to get my head around it. The confusion is because there are so many different hardware configurations openLRSng can work on - but the configurator is only setup to install the latest firmware by default - the pulldown just determines which style of hardware it's being built for.
To install the "stock" firmware you'd have to first figure out what the stock firmware from HK is and I have no clue nor any idea how to tell what it was. Honestly anything but ng is pretty much dead at this point from what I can tell so there's really no point in that.
I think you're closer than you realize. What you've been calling "stock" is actually the latest version of ng - and it sounds like with that you're actually getting things to work ... just with almost no range.
Can you hook your TX and RX up and take screen shots of the settings screens for them? Or save the settings to a file and attach them so I can take a look at your config.
What antennas are you using? Just the stock? They're really lousy antennas and while I haven't range checked them or flown further than 20 feet from myself with mine so far I plan on replacing them before trying to fly with it for real. It could be you have a bad antenna. Since you have 2 sets have you tried swapping them around? You may want to try some better antennas. Even a simple "sander style" (see here:
http://www.fpvmanuals.com/2011/03/23/make-your-own-lrs-rx-antennas-sander-style-and-turn-style/) 1/4 wave would work better than the stock antennas. I've got some connectors on order so I can build some better antennas soon.
I'm guessing you're still using the stock antennas and that's what's causing your problems. They're better than nothing...but just barely!