There are only three places I can think of that would put coolant into the valley like that: (1) front crossover (2) oil cooler inlet tube (from water pump to the oil cooler) and (3) the soft rubber heater tube that runs from the heater manifold (rear crossover) under the intake manifold to the throttle body (I have the SCV6 model, but I assume the V8s have this as well).
On the front crossover, are the inserts all the way down into the block? When I pulled my front crossover, the pipe ends were degraded, and the end ridge of the pipe stayed in the block when I pulled the pipe. I had to dig the ends out from the block separately.
I think (2) is the most likely culprit. Did you replace the water pump as well? There are two gaskets/o-rings that need to be on this tube - one on the tube end going into the oil cooler, and one on the tube end going into the water pump. If you used a new water pump, it comes with a gasket already installed as I recall - so don’t use another on top of it. If you kept the old water pump, its possible those gaskets are worn out.
The other thing about that little tube is that its hard to get it to sit right when you’re putting the pump back on (assuming you had the pump off). But you should be able to spot that problem readily with the intake manifold off.
You can buy new gaskets and a new tube, but depending on your mileage, you might want to replace the pump as well at this point.