New rebuild has odd vapors?

so I had my 318LA rebuilt over the summer. A list of components...
.20 over bore, stock pistons w/cast rings, whiplash cam, roller rockers,Performer intake and carb.
Broken in w/ approx. 120 miles on it now. Initially had an intake leak that I corrected.
Before and after oil change I noticed a slight puff on drivers side exhaust.
The other thing is I have a slight vapor out of either valve cover at shut-off.
Plugs look great. Car runs good, except for a slight miss.Compression check is 140-145 across the board.
When I adjusted the edelbrock 1406 idle mixture it seemed to improve a little. Carb was on car prior to rebuild. Unknown what previous owner did.
The one thing not changed yet is the old distributor.
I'm wondering if I could have a compromised head gasket on driver side? I did notice the water level in radiator down some.
Any thoughts on this?