IMO the longer 4.180' stroke will get you better ET's. the 1.44 rod/stroke
ratio will keep the peak revs on par with the 1.53 rod/stroke ratio with the
4.00" arm. the average street car won't feel the difference tho. but with
the cubic inch difference and greater torque from the 4.18" arm you'll get
some noticable difference from the 408, not so much from the 416. Long
strokes & smaller bores make for KILLER street engines.
the custom JE slugs that come with it @ .070" over (4.070" bore)
and you got a 426. however make sure you sonic test the block first.
as long as it has .200" on the major thrust side your good to go.