Coolant in engine oil, need advise?

I gave my son my 1993 88 since he was down on his luck, it has 155K mile on it. I've never had any problems with it and I've put over 100K on it. He had it a week, called me and said it wouldn't idle, but drove alright. He checked the oil and said it was tan looking, I told him it was coolant. He was a few blocks from his place so I told him to drive it home. Didn't make it, said it put out white smoke, but engine didn't make any unusual noises.

I'm hoping it is just a bad head gasket, but would like to know if anyone else has had this happen. Or if you have any suggestions on what else it could be. I've overhauled quite a few V8's, so I know I can do the work, but would like some imput from other.

Thanks,
Bob G