For $2000 you can get these
Stage 1 Heads for your 3.4L for $750.
You could get a stage 1 "package" for under $2k @
http://milzymotorsports.com/
I'll see if I can track down some stock heads for the 4 & 6 cylinders online. The head(s) will hav a core charge usually for your old heads untill you send them back.