Copper Quack Rabbit

Disabled Veteran looking to get into hunting again. Bought a DTI Del-ton 308 ar 10. I have been searching the internet for days and can't find anyone that sells uppers for it. I'd like to a 243 upper and maybe a 6.5 Creedmoor and a 7mm later on. Anyone tell me where I can find options or am I just being too cautious and just about any upper in ar 10 will work? Except maybe Palmetto state.