Alan
Your going to to have to run a looser lash adjustment, you don't want those valve hanging open. The cam you are running is a tight lash cam. My 500 in Engine Cam called for the same thing. I had to add .012-.014 extra to spec on camcard do to expansion & contraction of alum block & heads. This was recommended by cam manuf. and machinist. 1000s of passes no problems. set valve lash .006-008. cold, warm it up and see where you are at probably .020-.024 and go with that.