Reply to "Head selection"

1)- The extra 45-or-so horses comes mostly from the higher compression. But the closed chamber combustion chamber shape is a more efficient shape so that contributes, too. Many closed chamber heads are machined for an adjustable valvetrain which contributes to even more efficiency and power (with more aftermarket parts). There are closed chamber 2V type and closed-chamber 4V types. This last is the legendary "Boss-351" head. There are also aluminum versions from SVO and P.I Motorsports, that reduce engine weight subtantially for better handling, are easily repairable via welding and are already machined for an adjustable valvetrain. Iron 2V or 4V heads are scarce and nearly as pricey as aluminum while being virtually unrepairable if things go wrong inside.

2)- not necessarily, although adding the full "Boss" conversion with roller rockers will allow the use of mechanical cams in place of the hydraulic type, etc. Full roller rockers decrease the engine's loaded oil temps by 15-20 degrees, but add no extra power. Reduced oil temp is valuable at very high engine loads such as in competition.

3)- Whether you do this of not is a personal choice. Some guys are content to run 'only' 275-or-so horses and 150 mph in 5th. Others are not satisfied until they can run away & hide from that $78,000 Viper down the block. Your call....