Are you sure about your diagnosis?
1. When you say: "roller rockers seized" What does that mean? The roller rocker consists of a trunnion (could be roller) , and a roller tip. Did your tips seize, or did your trunnions fail?
2. Intake gaskets double stacked and not sealing well? Please explain. Double stacked, I understand. But how does that translate to oil consumption? What does a "ton of build-up" look like to you? Discoloration of the intake tract, or actual leak path evidence? Because if the intake manifold gasket was leaking enough to suck oil out of the lifter galley then it probably wouldn't run. Something is goofy here.
Do yourself a favor. If the heads are still on it, clean all of the surfaces, and check the fit of the intake to the heads with no gaskets. Since it is a new block casting, It is entirely possible that your deck height is incorrect, (too tall) and the assembler didn't make a "mistake" vs installing double gaskets because he needed to fill the gap. It takes some effort to make a mistake like that.
But far more important.
Bent push rods + stuck trunnion = lack of oil at the top end. Scored lifters, and a scored cam? You have an oil problem. IDK why you are not getting oil to the top end, buy you are going to want to prime your oil pump, and verify the oil squirt out the pushrods and lifters. There is a restriction somewhere, and your top end is going dry. Bad rockers? NO way! The factory pedestal rocker had NO rollers. When properly lubricated, there is enough lubrication that they can slide on the tip for 200,000 miles.
If it were mine, it would already be in the crate going back. You have an unresolved top end oiling issue, and it's not going to fix itself with new rockers. Metal has been recirculating in your crankcase. It needs an oil pump, and a thorough cleaning. Which includes bearings. I see a lot of symptoms, and no root cause. I'm going to say it now. Unless it had the wrong lifters in it, you haven't fixed anything. Whatever was wrong is still wrong.
