Hi and welcome to the forum
have a read through my journal i made a while ago it may give you some ideas.
http
/www.fishforums.net/index.php?/topic/340115-large-empty-tank-and-thinking-of-oscars/
7x3x3 is a great sized tank and can host pretty much anything with a few exceptions so you really need to research and take your time when stocking it. there are so many species out there to choose from.
personally if this tank was mine and empty i would look at setting up a bit of a species tank using larger fish. if you read my journal i had a real mix of fish which were all super stunning examples but the mix really didnt quite cut it for me and looked too mish mashed. ever since ive kept kind of species tanks and in my eyes its defo the way to go.
looking at your current stock choice i would leave out the texas. i had 2 of these in my tank and had nothing but trouble from them, stunning fish but aggressive.... oscars top your list, does this mean they are your first choice? if so why not set the tank up just for oscars? they are a very common fish but truely stunning with great personalities
4 x oscars
8 x striped/ filament/ melon barbs
1 x nice show plec Leopard/cactus/gold nugget/panaque etc
2 x larger cats - megalodorus are a great choice
it doesnt sound much but trust me when they are all fully grown plus with bogwood and decor the tank will soon look full. if oscars arent your first choice then as i said there are so many cichlids to choose from but i would keep south americans or central american not both together. CA are generally more aggressive and may not mix very well with SA cichlids.
clown loaches as stunning and active as they are in the shops will lose their beautifull colouration and they do go quite dull in time and also quite fat, chunky and large. many people will never have seen a fully grown clown but they really are nothing like what you see when you buy them young.
another idea that i would love to do one day in a severum tank. lots of wood and a good group of gold severums or red spotted severums, i saw a display tank with just this and it was awesome, add a few cats and dithers and wow...... talking of dithers i see you have chose silver dollars. these are a good choice as they get big, are fast and can handle a bit of nipping etc pretty well. these do get big though and can take up lots of room especially when in a group which they prefer. a kepy larger barbs in with my huge oscar with no issues at all so i would go for these instead personally. more colour and you could have a few more making it look more natural.
any way the choice is endless so take your time and if you get time read through my journal as it may give you some ideas you didnt have before. keep us updated too as i would love to see this when done