quick vortec cylinder head question

[69heavychevy]

i just came across a pair of vortec heads for $80, since i need new heads i'd figured i should go ahead and upgrade from my 993's. my cam has a max lift of .479. ive read all kinds of different info on how much lift they can accept before you have to machine the valve guide (anywhere from .420-.480). I already have comp cams 981-16 springs, will they work to give me more lift or am i forced to go with the beehive spring...and money is an issue here

thanks in advanced guys!

[69heavychevy]

did some more research and decided to go ahead and try the 981-16 springs. no that thats out the way, will the mexican vortec heads actually have hecho en mexico stamped on them or is it based by years??