speaker recommendations

Im putting these in a 66 Dart and I purchased the adapter to change the stock factory front speaker to dual 3.5" speakers. As for the rear deck speakers I am going to have to do something differnet back there as well since my roll bar goes thru those holes and I had to completely close off the rear trunk because of the battery in the trunk. The reason I ask about a better speaker was I hooked up the ones I bought to another radio by themselves and they sound awful. Im not worried about great sound since I will be running dual exhaust with very loud 3" exhaust. Might not even be able to hear a radio no matter what speakers are in!
But thanks for all the recommendations.
Rod