Okay so this tank is a stupid footprint, it's very limiting on stock options, for the current tank you have now. So most definitely would not add a BN in this tank
But they'd work in a 200 litre absolutely no problem. And good, get the 6 garra when you do upgrade, because as you are seeing, they bicker among their shoal. So they should ideally have others around to spread out that aggression and let them sort out their social hierarchy. Only 2, they'll fight more often and it's not as targeted. Luckily panda garra are the most common garra species in the hobby and much easier to get your hands on more.
Honey gourami rarely, if ever, have iridovirus that the dwarf gourami have. You'd be pretty safe with them, but honey gourami will require different water conditions than garra, who do best with increased water flow and oxygen, where gouramis aren't huge fans of flow and would be stressed.
So, I'd look at something that would be okay with a little extra flow.
Stocking I'd go:
15 leopard danios (they will provide a fantastic shoal in a 200 litre)
6-8 panda garra
1-2 BN pleco
There's few "centerpiece" fish suited for higher flow that don't already inhabit the bottom level, and with the garra you may be hard pressed for adding other bottom dwellers. I'd treat the plecos as your centerpiece in this setup and go for a nice pair of whatever morph you like best. BN plecos aren't super shy plecos, so you'll see them out and about more. I'd put higher priority on a larger shoal size for the danios because they'd provide you a ton of visual dynamics to the tank in a larger group. You could go way more than 15, but I feel 15 would be a nice beginner number for you.
As for cycling, if you move your filter, hardscape, media, plants all over to the new tank, you haven't lost the cycle you currently have and wouldn't need to re-cycle it. Just add the new fish in batches to build up your current cycle.
Now, if you are like many of us, you'll get that 200 litre, keep this current tank and get yourself a group of 3-6 honey gourami (1 male 2-5 females) and set it up for them and perhaps 6 trilineatus cories (false julii) if you like honey gourami. Then you'd have 2 tanks