Ill just throw you a combo here so you have an idea of what i would use for a middle of the road install like what your talking about useing a stock head unit
I dont use speakers that are not round like 5x7's or 6x9's round ones sound better so you would have to get some plastic plywood type stuff in 1/4" and make a plate to mount the 5.25 rounds in the 6x9 spot, and an aftermarket head unit would prolly be cheeper than buying an interface like the clean sweep like I said this is just middle of the road stuff you can go cheaper and still sound fine or more expencive