Tank Mates For My Upgraded Tank

Hi all So for the last few months I've been running a very old 60L tropical community tank which was home to a pair of honey gouramis, 10 cardinal tetras, 6 panda cories and 5 otocinclus catfish. The other day I noticed that my tank had started to leak and my partner said it couldn't be fixed with the fish still in it so tragically I was forced to upgrade to a much nicer 140L tank which my fish are now acclimating into I'm now looking into additional tank mates for my fish and was hoping for some advice.
I was in the fish store yesterday and they had a breeding pair of rainbow cichlids which I absolutely fell in love with and in a sudden rush of blood to the head asked to reserve them without knowing anything about them. So I was wondering (before I make a terrible mistake) if they'll be okay in my new set up, or whether they're going to pick on my cories. When I manage to repair my other tank I'm planning to move my otos back into it to make room for two bristlenose plecos. I was also hoping to get five or so dwarf chain loaches. I know that this would be pushing the bioload of the tank, but if I kept up obsessive tank maintenance do you think it would be okay? Lastly, I would like to know if (to push the bioload even further) I could add another fish or two that will stay near the top of the tank with my gouramis? I looked at hatchet fish but decided I didn't want to deal with suicide attempts every time I went to clean the tank but I can't think of any other species that would work in this set up. I'd be happy to get another few gouramis as long as that wouldn't upset the ones I have. 
I have fairly soft water with a pH of about 7.2 and I keep the tank at about 23 degrees.
Any advice would be very much appreciated

Grrr okay, well I'm happy enough to give up on having chain loaches. I thought they were cool but not enough that I'd put my very much loved cories at risk. I loved the behaviour the rainbow cichlids were displaying and made me certain that I definitely do want to try keeping a mated pair of cichlids. I originally wanted kribs but all the research i did suggested that while spawning basically all of my other fish would be at risk which I definitely don't want. Am I best to try to find a pair of apistos for my 140L and a pair of rams for my 60L?

Gosh they're lovely! I especially liked the flag cichlid! I have never seen any of them in stores though I might have a look around for some private breeders and see if i can find any though

errrr..... don't wish to be pedantic (oh, alright - I do), but 2 male + 4 female doesn't = 8 gourami. 

I know you said in another post that shops only have one apisto in stock at a time but they do better with company. Females don't look like males; they are smaller and plain brown in shop tanks - is it possible you overlooked the females? They do change colour when they settle in. The females of all species of apisto are yellow, even the species where the males are blue.

I've just looked at kuhli loaches in the community creator (or coolie loaches as they are there) and am very surprised to see that they have a rating of 8cm each. I was always under the impression that they had a small bioload because they were so thin. If it is a kuhli loach and you decide to keep it, it would be much happier with some others of the same species (there are a few different species, most of them striped) and despite the CC I would say you'd be OK with them. Think of them as a replacement for chain loaches.

Oops, missed the rams at the bottom of the list 

I would stick with just one species of cichlid. And since you don't sound too keen on keeping an unwanted fish, see if you can rehome the kuhli. Like most gregarious fish, they are best with others of the same species. They will shoal with related species if forced to by lack of their own, but this is very much second best for them.

Kuhlis do need sand because of their habit of burrowing, gravel can damage their skin. But they would be fine for the 60 litre when you get that back up.
 
Re the cichlids, I haven't actually asked you yet, what is the size of the floor of the tank? If it is a long or wide tank rather than tall, you might get away with both. If it is a tall tank with a small floor area for the volume, stick to just one. It's all down to the amount of floor space available for territories.

That's just slightly longer than my old 125 litre (that was 81 x 36cm). I wouldn't keep two species in my 125 litre.

Apistos like caves to spawn in, while rams like to lay eggs on the surface of flat rocks, if that helps with the decor layout 

Ooh okay, I've just read that you should keep apistos in harems so if I can get hold of some, should I keep one male and three females? Or will that make things too stressful for my cories?

Okay, I can certainly do that and the gouramis? will two males be okay in my tank? or would i be better to stick to just one male and lots of females?