596 casting or 308 casting for mild 360 4bbl

popinsmoke said
Gentlemen,

I am building a mild 360 4bbl in my 78 Magnum, The short block is the stock low compression 360 2bbl that Ma Mopar made millions of.
Now I am in the process of installing a Comp Cams XE268H complete kit as well as an airgap intake and street demon 625 4bbl carb.
The lean burn system has been ditched in favor of the MP electronic conversion with the orange box.
Plans are at this time to run the big outlet dakota exhaust manifolds in to a 2.5 inch true dual with an X pipe.
So my question is the car has 596 casting heads currently sitting in boxes that came off the car and 103k miles, I have access to a pair of 308 castings at the local bone yard as not allot of Mopar guys frequent my yard.
Everything that I have read says that the 596 castings are the best of the smogger heads but the 308's are the best pre magnum head, my question is how much better?
If I am having 2.02 valves and bowl work performed anyway is there that much of an advantage to the 308 "swirl port" design $ for $?
Also looking for the MP head porting templates anyone know a good source to find them?
Thank you in advance for any advice.

IMO not worth the big block swap unless you have the donor car with it for the mounts and oil pan at minimum, the transmission, the kickdown, thtrans crossmember, and driveshaft at most.
The heads on the engine will be fine if you go through them and add performance valves and get a real valve job in them. IMO the added expense of 308s is not worth it. Take your heads, have the shop fit them with performance 2.02/1.65 valves, and have them do a modern 5 angle performance valve job. That valve job and valves will get you to very close to the template porting work and for what you're doing they will be more than fine.
You don't want a DCR of 9:1. You want a DCR of less than 8.25:1 and a static ratio of no more than 9:1, and you won;t reach that without pistons or a ton of milling. Milling is not the means to that end - cost wise you will spend a lot more beyond the milling to make it all work right and the jump in compression will not provide much additional power in and of itself.