What kind of power could I expect if I....

...bored out my 420a .040 over and got some head work done? Haven't really seen anything on here that really gave a good whp estimate. If there is something that I over looked just post a link and i'll get rid of this thread.

EDIT: Throw some agressive cams and adjustable cam gears into that mix as aswell.....

Well I have been looking at a head that gaurantee's 40hp to the wheels N/A and even more with a turbo so I might get it and see what it does on the dyno.

Is it a mass produced head? If so who makes it, and how much? Usually something like that would be pretty pricey huh?