i need help w/duster engine

I know what claying is...we did it to our.Whaley terminator outlaw engine.
ok a couple of things......
i am not sure...what i read so far...
i cant put a roller cam in this because i have stock length valves..?
and i wont be able to run enough spring pressures.?
what if i dont go .600" lift...like chepstreet duster said..?
Am i just stuck with this..?
Again maybe i am missing something..but why cant i get the data in need
by measuring the valves with the head still on?
i can do a measurement at 25* before and after if i need to..some one mention'd that?
aarrrrGGG....?
Mel...