oil in cooling system

i just bought a 84 crx dx, i knew it had overheating problems. i thought it was the thremo so i replaced it but when the coolant drianed out i noticed there was some oil in it and was just wondering what it could be from, i think its the headgasket but i want to make sure before i replace it.

i have a 1990 crx si head and wondering if that would fit on crx dx block.

thanx, David

Could be just the head gasket. If it had prior overheating problems, there could worse damage than just the head gasket. Remove cylinder head for further inspection

alright, thanks hopefully it not bad
thanx