First off the description on R4 block is wrong. P7 heads are a lil different bolt pattern. P9 heads have a 4.500" bore spacing.
You guys get way to caught up in numbers. You have these numbers from builds you read about memorized as if it is the gospel. Displacement numbers. I have ran from 421-468 cid with W8 heads. I love a big bore. 4.185" is small and has its limits. Current R5p7 is 4.182". Just nature of the aluminum eei block. With R3 I'd start at 4.200" 4.250" if you aint scared. Stroke simply moves the rpm power range. I like stroke. It feels better and you can shift lower. Displacement by stroke is a lot the same way except with power adders.
Long story short you dont have to build 440 cid. It just a number
The only reason I mention big Cid was to lower the rpm on the P5 heads.
I think that these heads were designed for 10000 rpm on a 358 cid.
IMO the bigger cid would lower the rpm and power ban.
