NBT,
So you need extra exh duration to make HP? The turbo guys didn't get the message....nor Jon Kaase who won the EMC contest with a 400 Ford engine that made 660 hp. It used a FT cam that had 246/238 @ 050 duration....on a 98 LSA & 92 ICL. Hmm....
It depends. So yeah, single pattern cams have their place but its usually over valved on the exhaust side. Take a look at a 632 Chevy. Most of the cams for those have a 15-20 degree split, maybe more. The current trend is huge strokes and small exhaust valves to get the biggest intake valve you can. So it takes more time/area to use blowdown to it's most effective value.
Its not 1985 any more so don't build an engine like it is.
I couldn't care less what the hair dryer crowd does.