AFAIK the engine and trans was bolted to the front subframe (aka k-member) along with some other stuff like the steering gear, then the body was lowered down onto this assembly. So room between the inner fenders have to be wider than the engine from exhaust header to exhaust header.
Also, the engine bay of an e-body should be the same as a 1971/72 b-body. At least from rad wall to firewall and inner fender to inner fender. The cowl area is different as well as the room in front of the rad wall.
Tim, sent you a pm. Couldn't get through to you via mail...
Thanks Jens...I wasn't fully clear on that. And I have read many articles stating that the '70-'74 E Body and '71-74 B Bodies shared the entire engine compartment including cowl structure .... although as you note, the area in front of the radiator wall is different.
I'll check the PM...don't know why mail would not have gone through...TB