Matt: I have a set of the P5 "wedge" heads, and checked on the R4 blocks. As far as I know they are 8.8" deck height without lifterbore machining which are the reasons I did not buy this block. I decided to go another route; use an alu sprintcar block, and change the lifter galley (involves a lot of fabrication and welding). To stroke it spacers would do, and longer sleeves is no issue. But the problem is the headbolt pattern is also different, so I just put these heads on the shelf, maybe it can be done in my next life!! (LOL) Also checked them on R5 block, did not fit there either....

If you do this and add spacers you should do something with them to get coolant flow high enough to take away heat from the pistonrings at top dead center.
It will be a costly project unless you do the machining yourself.

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.

Will the P9 heads bolt directly onto an A8/R4 block ? Or should I say could I remove my P5 heads and bolt on the P9 heads? What are the valve angles and flow numbers of the P9? There's not a lot of info on them.

Different bore spacing Marty, plus the bolt pattern is most likely different

$1995 blocks just isn't going to happen, the return on investment just isn't going to be there. It's all good and well saying they will sell, you're not the one kicking in the $200K and 1-2 years doing it. If you're that confident, mortgage your house and do it.

So the new R4 blocks and old R4 blocks are different? I was assuming they were the same just a different deck height. I was wanting to bolt on a good cast P5 head or try the P9's. I can't run a blower and billet heads in my class. Thanks for the info.

Sorry Marty, I've had a brain fart, I thought you were refering to the Nascar P8 heads that go on the R6 Block. They have a 4.5" Bore spacing. As far as I can tell they bolt up to the R4 blocks, Brett Miller had a pair as seen here:
https://board.moparts.org/ubbthreads/ubbthreads.php/topics/1418930/p9-mopar-head.html