Heads 1973 360 la

hey grumpuscreature why do the guides need cut to run over .500 lift? i have a comp .501 lift cam(i know thats borderline) on my stock heads in my warlock am i at risk of something coming apart? ive been wanting to pull the heads and have some work done to them so any info you have on this subject would be great. i have about 2000 hard miles on this 360 in my warlock and so far so good no problems but now you have me wondering.....