NZ, while a well tuned 440-6 would beat a hemi to 60MPH, in the quarter mile it's the hemi that wins the race. I've owned both type cars, and given equal mods, the 440-6's out-pull a hemi in the lower RPM ranges, but up top (4500RPM and up) is where the hemi is KING. Back in the day, a 440-6 pitted against a hemi in a quarter mile race would be in front almost all the way down the track, then just before the traps, the hemi would just walk on by and win. As far as valve lash adjustments, the later (70 and 71) hemis had hydraulic lifters to eliminate the need for adjustments. Now my 472 hemi I have in my 71 is another story, that motor makes torque right off of idle and still pulls HARD at high RPM.
The newer hemi motors are sort of a semi-hemi combustion chamber, the two plugs are for better emmissions and to get a complete burn of the cylinder charge. I think they are a good motor, and I plan on getting one in the wife's next car. As far as about 99% of the general public is concerned, they have NO idea what a hemi motor is, all they know is the name and it's supposed to be the best.