I have a question. See the two speakers dangling from the CRT.....what would be the best solution for my speaker panel? I was planning on using a Nintendo style single 6" speaker. Should I just use one of those speaker lines and connect it to that? Or will I lose sound because there are supposed to be two channels? Or should I use an amp somehow? I have a lapai 2020 amp on order for this build. Or should I just put both stock TV speakers over the speaker grill?
My first TV rodeo....so opinions and knowledge welcome!
If you're using an original NES the sound is mono, so you're ok using either channel.
You're probably not ok just hooking the speaker leads from the TV up to a different speaker because:
The original TV speakers are probably some high impedance like 16 or 32 ohm.
The larger speaker you'd use would most likely be 4 or 8 ohm, which is too much of a load for the amp in the TV.
I'm not a fan of using the original TV speakers, but it's an option.
Their frequency response is probably centered around the vocal range, so the highs and lows will leave something to be desired.
(even though we're talking about old arcade machines that didn't even use a wizzer cone, let alone a tweeter)
Personally I'd stick to your original plan and use one big speaker with the lepai amp.
It will be more like the original Nintendo cabs and you can mount the amp inside the coin door to adjust the volume.
You may end up only using one channel of the lepai amp if it's not bridgeable. A lot of times those little amps aren't.
You could get a dual voice coil ceiling speaker, but personally I wouldn't spend that much on a speaker.
On the CP art, I'd redo it to match the controller. 
EDIT: Strike that. Since you don't actually have them labeled as A and B, I think they're fine.
The first arcade button in a row which you'd hit with your index finger is usually the main action button, which would be attack.
From an arcade game standpoint, I think it would feel weird for the attack button to be on the right.