Which year or years 360 is best

The factory head Magnum design is fantastic for the CID range of 273-340. They will work well in upgraded form (EQ/RHS) on 360cid.
Just my opinion but I don't think even the upgraded Magnum heads are the wisest choice for a larger-than-factory engine starting from a blank slate. Especially one that will be racing and with a 4" stroke engine. However when budget is an issue they will produce decent results. IMO, once you think they need to be ported, move up to RPMs.