You asked for it...
First of all, I think the SBC is a damn fine engine; it's been the standard of V8 performance to which all others have been compared since it was introduced in 1955. Yup, that motor is 48 years old...
Second, let's examine this mythical beast known as the high performance "street motor".
The engine should be capable of running on the street, with decent idle characteristics and low-end torque. For longevity and practicality, the engine ought to develop peak power at around 5500-6000 rpm.
To me, a street motor is just that; it will withstand the rigors of driving across town without overheating, puking, or stalling. The test is simple: (1) Will it run on pump gas? (2) If you install it in front of an automatic transmission, can you use the stock torque converter? Let's be honest- if you answered 'no' to either or both questions, you have a race motor on your hands. The Lunati engine in the article is definitely not a street motor, and it certainly does not fulfill their own objective. I don't have a clue as to what they mean by 'longevity', as the stock bottom end and iron crank of the SBC will be pounded to death in a very short period of time at 6000 RPM. And I'd be interested to know their definition of a "smooth idle".
You need a bigger cam to make this small cylinder work, but there are limits due to the small displacement. Fortunately, the relatively long stroke for this displacement engine helps low-end torque, so the engine isn't all that cam sensitive.
Maybe at 10.25:1 compression. Lower that to a streetable level and tune the motor for pump gas, and I'll doubt that motor would run worth a damn below 1500 RPM. Not good if you're running a stock auto-tranny. And why would you turn around and reverse the primary characteristic of a cam like this by sticking it under a dual plane manifold and a small carburetor? This is an engine in conflict with itself.
This business of LSA: A cam with a lot of overlap (like theirs) runs well at high RPM because the overlap is conducive to flow through/scavenging. At high RPM, the flow through the engine is of very high velocity and carries a lot of momentum. Narrow LSA, long overlap cams make their best horsepower with large, single plenum manifolds, and oversize carburetors. That lopey idle that so many guys are enraptured with is the result of inconsistent cylinder filling, a direct result of too much overlap and duration. These guys have stuck on a dual plane manifold to keep intake velocities up in an effort to just make the thing run at low RPM. So what you have is a seriously compromised motor that burns a lot of gas. These guys would have a much better running engine and could get a "corrected" 343 HP in a much more reliable manner by using the right block and heads. Would have cost 'em less, too, 'cause they wouldn't have had to rework the heads.
On a motor that spends the vast majority of time under 6000 RPM, the type of cam that works best is one with a wider LSA and lots of lift, the idea being that at low RPM this high velocity flow is diminished, so you have to compensate by maximising the event of each individual valve event. This is accomplished by lifting the valve as high as possible to let in as much fuel/air as possible, and separating the intake and exhaust events a little more so as to more efficiently evacuate and fill the cylinder.
