Engine smoking, some help please

I have a 1996 Jeep Grand with a 5.2L. I just changed the motor and after one minute of it starting (starts fine), I start to see smoke coming from the back of the motor what looks like from the read cylinder head area, no where else. The rear seals are dry and it does not drip oil at all. I am afraid it might be head gasket related and have not checked the compression yet.
Ideas Please?