The low deck block is stronger than a RB/HEMI block. Thicker main webs, Shorter/stiffer cylinder wall, shorter pushrods. Shorter piston. It all just adds up to a better package.
I probably wouldn't phrase it exactly like that. Yes, most people feel the low deck block builds a better wedge for the reasons you stated. But that doesn't mean it make a better Hemi. The pushrod angle gets even worse if you make a Hemi out of a low deck. Thicker main webs don't make up for the cross bolted mains on the Hemi block. If he wants a Hemi, there are still some of the old Chrysler 366 cu in Hemi cranks out there. And new light weight rods and pistons are easily available.
