1984 Dodge Aries A variety of things!

Engine Performance problem
1984 Dodge Aries 4 cyl Front Wheel Drive Automatic 58 000 miles

I recently got a 1984 dodge aries from my grandfather and right away I started to notice problems that just got worse. It has 58 000 kms on it but it sat for a very long time. I picked it up from Whiterock and proceeded to drive 780 kms to my home town. On the way I noticed a temperature spike and the heater wasn't producing heat. I figure it was lack or rad fluid and I was right. I topped it up and continued to drive, and stopped for some windshield washer fluid at the gas station. When I started the car I noticed it had an extremely rough idle, the car was shaking, and a large cloud of smoke came from the exhaust for about 5 seconds. The smoke went away but not it idles rough and drives rough until I hit about 25 km/h. The rad fluid keeps running low. I can't see any visible leaks and I suspect a cracked head gasket. The oil looks normal when I check it, and the smoke coming from the exhaust was white. I suspect a cracked head gasket? Hopefully that's not the case; but with all of the rad fluid disappearing so fast I only assume that's what it could be. I can't be sure that the rad fluid isn't pooling somewhere when it is leaking because I haven't had the chance to get under it yet. I did an oil change. Any suggestions?