I've made 730 HP N/A on Oregon pump fuel with a 400 block with the Mopar brand ductile iron main caps with 517 C.I. with one 1050 Dominator with a set of Indy SR M.W size port heads, that motor had right at 10.8 to 1 compression and lived on the street and at the track shifting at or above 7000 RPM on all runs.
I try to make sure I don't use 440 blocks for any build over 700 HP, N/A or other wise after having three 440 block cracked the main webbing between #1 and # 3 cylinders
No problem with good sonic tested 400 block yet at or above 775 HP N/A so far