Classic rock album covers

Is it illegal to make copies of album covers and sell as art? I have made some really cool wall art ( I dont know what else to call it ) and my friends always want me to do their favorite old lps for them to put in their home, listening rooms and even their offices.

Is there such a thing as free domain after a period of years? Are most of these people even alive ( remember it was mostly the 70's) or does it go back to the evil empires ...the record lables. Would this infringe on copywrite laws?

I have a 60k color printer and access to all paper stocks for a really impressive look ...

Give me some advice

Kelton