You'll really want a cam or cams (if VTS) to feel the full-effect.
With porting/polishing and cam its just easier to do it all at once while the head is already off - rather than pay for labour AGAIN at a later date,if doing it in two stages.
With porting/polishing,cam and re-map 20-30hp is well possible
Hows that grab you for a grand !!!!!!!!!