Some Ford help here. Having played with FE's and 6bangers for nearly 30years here it goes
The 330, 361 and 391 truck engines are externally the same as any FE except for bigger crankshaft snouts to be used for
heavy duty pulleys for compressors and such. But whatever engine one you use should be fine as this wouldn't be that noticable in scale.
The 6 bangers were the 240cid and the 300cid which were identical externally, and the 300 saw production all the
way thru 1996!