Rollers make sense for them to offer if they want to keep going. I would not want to count on a nitch market of a 40 year old car! I do like the drop in flat tappet solution because you don't have to change anything else. I would probably check the lifter depression when I bolt the rockers on since i have seen a 340 that needed spacers to get the lifter preload right...and then the variable feature could help.
