I never measured mine, but the JZ bore pitch is tiny at 3.622" (compared to 4.400" for the 250, 4.055" Atlas) which shrinks the overall length. The Barra may have inherited 4.080" pitch from the much older pushrod 144, 170, 200, 250.
The front drive and bellhousing lengths...??
Not much weight saving, only the JZ head is aluminum.
The JZ deck is only 8.543" (250 is 9.150", Atlas is 9.160", Barra 9.228") but the excellent factory JZ oil pan is pretty deep.
