The problem will not be lift as much as pressures. You have a lifter that's twice as heavy, a rocker ratio that acts heavier on the spring, and a cam that needs pressure. Unfortunately the head cant accept much for springs. I think you should save a little bit and have a set of LA heads done. Or get a set of take offs from someone upgrading. Run hollow pushrods and you dont need the shaft oiling. the mods to get real springs are costly, and a set of RHSs or Engine Quests will have the same issues... Cost to get usable. Porting wont help if you cant get a spring in it that controls things well.