The engine was originally designed in the 1990s for that rpm range based on what was standard practices at that time. 372 cubic inches, splayed 4-bolt mains added after cap walk was found during freshening, tubed lifter galley, W2 heads, Holley Pro dominator tunnel ram, two 750 Holleys, long ford 6 cylinder steel rods, welded truck crank 3.58 stroke, balanced, o-ringed, etc, etc. Doug Nash 5-speed and a lot of fun buzzing it. Eventually aluminum rods, better heads and more power split the mains out of the stock block. Made a lot of passes before it let go but knowing what I know now I would just buy a race block regardless of what rpm I want to run. On a side note, every time I build a smaller engine my car goes quicker and faster. Running a 312 cubic inch motor shifting at 9800rpm now and would never consider racing anything that needed shifted below 8,000rpm.