Yes, that is a typical sign of a spun bearing. As the engine warms the tolerances expand and the bearings cannot hold pressure.

 

I can't agree with the spun main bearing theory, when a main bearing spins the hole in the bearing is no longer aligned with the oil hole in the block, this will immediately stop the oil flow the the corresponding rod bearing resulting in rod bearing failure very quickly.
Even if a there was no knock from the spun main bearing, the soon to follow rod bearing failure will be heard for sure.

Installing oil restrictors in the heads will help regain oil pressure if it's being lost around the rocker assemblies, if that doesn't help ether a oil galley plug has come out, the engines bearings are worn out or there's a issue with the oil pump.

With the oil blowing out the valve cover breather cap I'm leaning toward to much oil going to the heads

 

Yea I'm thinking the rockers are the first place I need to look for sure. I as well don't buy a spun bearing, by now it would have shown itself. Will the restricters starve the top for oil though? I'm leaning towards rocker's or shafts being the issue because before the tear down we didn't have an oil pressure issue.

 

Easy enough to tell, just pull the valve cover off that was blowing oil out and start the engine, if it's flooding the head you'll know real quick, there should only be a small amount of oil coming from each rocker.
.080 restrictors won't starve the rockers, installing restrictors is a old school racing trick, FE racers realized these engines where notorious for over oiling the top end of the engine, engine builders found that a .080 restrictor allowed enough oil to the heads to keep the rocker system oiled while retaining more oil for the bearings.
I found the restrictor recommendation in a early Ford Hi-per Parts book back in the 70's when I was hotrodding around in FE powered cars.
Some call restrictors a patch for worn rockers or shafts, but racers where doing it to brand new engines as a performance and durability improvement.
It was secret snake oil stuff back then, just like the oil passage mods to the block.

 

This is why I got scared off of installing a HV oil pump in my rebuild..... I took the pan back off and put a standard volume Melling in......... I know there are modifications to support a high volume flow, but for a tame build it may not be a good option, and there are several horror stories that claim to be caused by HV pumps in the FE blocks....... Just my 2 pennies worth on the HV option.....

 

So last weekend I pulled both valve covers and let it run at operating temperature. I found no oil flooding the heads. So anyone have any experience with the scat 444 stroker kits? Maybe I need to start a new thread? If I'm gonna build this 390 I may as well bump her up on the cubes while we're there...

 

The heads won't flood at idle, only at higher RPMs.

 

Yea I revved her to 3500 and held it there and saw no over oiling. Had the covers off for about 20 minutes trying to get it to flood the heads.