head questions

I have a stock shortblock 71 340, reringed and bearings, comp xe284, home ported 1.88 J's milled .030 with MP thin gaskets. motor runs really well, I have a fresh set of magnum heads I accuired in a trade, they have 1.6 roller rockers and beehive springs on them . would I see much gain if I swapped the heads out?