I've found over the years that every engine builder or machinist tends to have their own set of points of importance when it comes to building or machining an engine. This isn't to say that any one of them is more right; they all have just had different experiences and have over the years tried different things to correct the problems they have seen.
I would never suggest just checking nothing and slapping a engine together. I check everything, including new parts. I've found metal shavings in brand new pushrods for example. I test fit the distributor prior to installing the timing cover so I'm sure I have clearance between the drive gear and block. Anything that can be checked, should be checked.
I don't know what model or how old your AFRs are. I can say that on mine everything was perfect. I checked rocker geometry on multiple valves on both banks and it was perfect. The machining on them is utterly amazing, but they are all now produced on 5 or 7 axis CNC machines. That may not have always been the case.
I don't know who's cast cranks he's had problems with, but I'm struggling to understand how a cast crank vs. a forged crank has more issues with the thrust bearing. If the crank endplay is correct and there is no preload created by the transmission, thrust failure should be a non issue. I would certainly like to know a whole lot more about this before just accepting it at face value. One worn out crank is certainly disconcerting, but its just that, one worn out crank. I can show you a bunch of busted parts in my shop, but it doesn't mean the part was always at fault for its failure.
The primary concern of a cast vs. forged crank is that a forged crank is more tolerant of detonation (just like a forged piston vs. cast). Problems with the crank and perceived problems or deficiencies with the mains are typically caused by detonation, whether the builder thinks that or not. Often it never occurs to them because they didn't hear it. Under hard use detonation will just break stuff before you hear it.
There have been millions of budget stroker kits with cast cranks sold over the years, yet the net isn't swamped with tales of crank failures. If you keep your plans realistic a cast crank will work just fine. Those plans aren't realistic if you are going to make 750HP with a blower and run the tune up on the ragged edge. If you're shooting for 400-450HP NA and are going to use street tuning there's no reason why a quality cast crank won't be good enough.
Hey, in the end we all tend to go with the advice we're getting from the guy we think knows more than us (or who does in fact often actually know more than us). You've got to do what you think works best for your budget. I can say that there's a point of over engineering though. There's also a point of being gun shy, and its when you're having to build a second engine and fearing what it would be like to have to build a third. Then something comes along that plays right into your worst fears. Just be cautious of the amount of conformation bias that may exist in this situation.
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Bullet Bob wrote:
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