I would like to run roller rockers on a set of 518 max wedge heads is there a difference compared to standard roller ones was told max wedge uses an offset arm per cylinder.

You where told wrong about the stock ductile M.W. rocker arms, all three years used the same rocker arms with the 1964 year models only not having the aluminum bolt downs stands like used on both the 1962 413 M.W. and all the 1963 426 M.W. motors. 1964 was the first year Mopar went to cast in rocker arm stands in the heads regardless of which size B/RB motor
Who ever told you that about the M.W. heads may have been thinking of some of the after market race only heads like the Indy 440- 1 that have the larger, wider intake ports that move the pushrod pinch area over towards the exhaust side of the heads requiring the use of offset intake rocker arms
IHTHs

thanks thats good to know as i am running a set of eddy victor max on my stroker 500 and they use the offset T & D rockers and the max wedge 518,s will go on a 426 build for my 64 330 with hilborn