360 & high lift cam
Any modern cam you want to run will need the guides and spring seats cut for dual springs and the positive seals... I have this done on every head I get done now. Doesn't make sense not to anymore.
Even with pocket porting, the "J" heads will waste a camshaft with much over .500" lift. They are just not made to flow that much. right at or below .500" lift, they really shine. It's not always about flow. With the "J" and "X" heads it was more about velocity. The duration figures on the other two camshafts is really too much for what you have.
I would say you've got the right idea, but I don't agree with this statement 100%. There are a couple things I see that I'd consider off. The general idea of "smaller is better when choosing a cam for a street car" I agree 100% with. If you blueprint the engine and really get a true 10:1 out of it, I don't think 230-240° will be "too much". If you don't get the compression, I wouldn't go more than about
225°@.050 because bolting the parts together will give you around 9.3:1 depending on the parts, and that's going to be sluggish below 2500.
The issue with LA mopars that applies to these heads as described is the pushrod angle. With any Mopar head, stock 273 to W2 and a 58° (factory) block, you will lose around .016-.022" lift on both intake and exh just because of the poor angles of the pushrod. Some engines will lose more, depending. So when you are looking to choose a flat tappet, you have to take off the lash figure, plus the loss thru the pushrod right off the bat. That leaves us with .480 out of the gate with the XE282S.
In addition to that, the statement that the heads don't flow so don't bother is not really accurate either. You want to give the heads the best chance to get the mix in... That means being open for the longest period of degrees as you can. If the heads peak between .350 and .450, and you run a cam that is really only .480 at the valve, and
245°@.050 , it's only spending about 100° actually above the .350 mark where the heads want to flow. You want to get the best lift under the curve for your heads, which usually means lifting about .050 beyond the highest flow rate (which is a guess if the heads weren't flowed) and keep the duration at .050 decent enough to keep the valve open where the heads will make good use of it. This would be especially true with ehads that are mildly or home ported because the low lift may not have been drastically improved by the work. I think I might suggest something like the XS268S with 1.6 rockers or up the compression slightly and use the 1.5s on the Lunati 60442 which would be rather hairy in this build but I think a bit better than the Magnum 292 solid.