Here we see my 70 340 with j heads beside the 318 , to built it like a 340 is a very good plan , i have already a double timing chain , hv oil pump , m1 la intake dual plane , but dont know what heads to choose. , the 2 last engine i buit was 2x 380 hp mopar crates but never played with a 318 ( surely not to make it a pocket rocket !! ) *** want a street driver so in a light 70 duster , 3.23 or 3.91 gears , and already have a 4 speed for it.