the 4.6 SOHC is a pretty wide motor and a DOHC is pretty fucking huge, its wider than big block. I think a SOHC could fit, but I really doubt a DOHC will fit into a nissan . You are better off getting the dimensions for the motor itself, which I know there is a pic posted up somewhere on the internet with the motor dimensions of the pushrod and mod motors.

http://www.mustangsandmore.com/ubb/E...imensions.html

I dont trust the mod motor dimensions. Im pretty sure the 4.6 dohc is wider than the SOHC