Howdy,
I have an 85 t/a, 305 mostly stock minus an edelbrock intake and a 4 barrel.
Runs fine, but after a couple mins of running she smokes from either side of the engine and appears to be coming from the flanges on the exhaust manifolds. They are indeed wet with oil.
Could that be a leaky head gasket?
when I got the car, she was sitting for like 9 years. I've replaced intake gaskets, exhaust manifold gaskets, dizzy gasket and valve cover gaskets. Never pulled the heads so never replaced em.
The leak appears to start around the #8 and 7 bottom of the heads
Any ideas?

 

I would guess valve cover gasket.

 

Or the back of the intake is leaking oil.

 

If you over tightened the valve cover when you replaced the gasket you probably cut the gasket. I would pull the covers back off and check the gaskets.

 

It could be an intake gasket but my money is on the valve cover gaskets.

 

I always use a torque wrench when tightening even the valve covers, can't remember exactly but think something like 7 foot lbs on the valve covers. This requires that I use my inch pound wrench and multiply by 12. Works great to keep you from over tightening the gaskets.

 

Another potential source of oil leakage from the back of the block area is a leaking oil sending unit (which is under full oil pressure all the time). BTW, it can still function when it leaks.

I recently fixed a persistent heavy leak from behind the block when I replaced my oil pressure sending unit at the time I installed new gages. It was an unexpected bonus that my oil leak went away!