I found a 360 R3 block P4532910 it only has 2 bolt mains but comes with 3 milodon 4 bolt slayed caps. I have 2 questions.
1. Are the splayed caps a good way to go on this block?
2. What kind of price would you put on these parts?

That's a nice block, 9.6 deck 59° lifter angle. Yes I would have the caps installed, plenty of room to do so. 2500 is the number I would put on a new block unmachined.

If the caps are already installed 2500 would be a very good price.
I've installed them on my Engine Master build with W9 heads. The block are plenty strong but require lots of machining depending on what you want to do. RE $$$$$
Roller lifters require the intake side machining in the lifter gallery. You remove the provision for the 3/8 head bolt. Then the lifter area needs help to use standard roller lifters. Again all this is money.
You could just purchase it and sit on it for 5 years. I would be it would fetch 5000 when you decide to sell it. LOL

I think the P4532910 is the casting number, not the part number. My block was P4876797. Sounds like the same block as mine. I wouldn't sell mine for less than $3k since tall deck blocks are hard to find now.

6796 block was on closeout for $696 back in the day.

I wish I took some pictures of the R1 block that my Dad and I used for the 416 in my car. Ryan at Shady Dell has a CNC program to do all that is mentioned above, turned out great!

R1 with W-2s, Geez Clark, did you set out to purposely build the heaviest SBM in captivity??

And people ask why my car is so heavy.........

We didn't really do it on purpose but it was what we had to work with.

Billy! You are speaking sbm quite fluently. You need to lift a W8 head.... it would surprise you

It's not that heavy Billy.

Its heavy, I had to turn the tortion bars up 4 whole turns after switching from an aluminum headed 360.

P4532910 is the casting number. I am told it has a 3.91 bore right now and has never been machined. It has sat in a corner of the guys shop for 8 years. It has some surface rust.

Now the next questions I know I will have to sonic it but any idea on max bore on this block? Does Rod Bloomer still have 4.25 360 cranks?

I think I will put this in my 4sp 65 Barracuda street cruiser.

Yes, I talked to him at Indy. He has a 4.25 kit that is drop in, and maybe a 4.5". He was telling me I could go 440ci on a stock 360 block.

I don't know the part number or the results of the sonic test on the R1 block I have. But, I do know that we settled on a 4.08 bore and it is safe to 4.12 naturally aspirated.