Help with 340 compression + cam change

Boy
one of the first threads I've read with consistent good advice AND responses from OP
What I'd do
what Rusty said- leave it alone
but get tune perfect
then try 4 degree advance and see how you like it - if you like it better then maybe a shorter cam with more lift like Voodoo, Howards -
and 4 degrees retard and see how you like it if better you could go to a slightly bigger cam say the Comp XE274- even though the duration is the same as now it is a bigger cam- or .904 grinds from Lunati, Howards, Bullett, Engle
Actually if you want to make a meaningful difference go solid and work with Jones
IDK if Jones has any Mopar hyd grinds except for his excellent "low compression" grind which is much smaller than what you are working with 256 .305 cam lift but 50% larger at .275 than The DC 260 grind
single pattern/ dual depends on intake/exhaust ratio from carb to exhaust
forget roller tip rockers as stated above for your lift needs B3 kit is a must etc
I do recommend oil through the pushrod lifters and pushrods to help the rocker cup live
8.5 motors can be made to run well
anything else is going to require heads, cam and lots of $$$
cheers