Glenn thanks for the post. And I have read up on the problems with lift on the stock vortec heads. after reading several articles on this matter including the article in your post. have found that some of these articles are not quite factual. The article you posted refers the the max lift on these vortec heads is .420, when that is not the case. The stock cam that comes in the L31 350 vortec has a .428 valve lift on the ex side. Here is one article that I have read about on how to install a larger lift cam without head removal on the vortec head.
https://www.thirdgen.org/forums/tech...ortec-lt4.html