As others have done, I have substituted the silly original engine for a V6 using the standard Technic cylinders etc. Or at least, I will, I only have engine parts from a flat-4 currently.
I've retained drive to/from the cabin steering wheel via a few chassis mods to give space to move the lower UJ further back to clear the rear N/S engine casing. Its tight but there's clearance everywhere, just.
By a stroke of luck, the recess in the bonnet underneath the central bulge is perfectly placed to clear an inlet plenum