Thanks Rob. Read all that a while back, been in contact with Mike. No answers to be had for Magnum heads. I spoke to PRW today, they minimize any concern about weakness without a girdle with my setup at about 300 lb open. Also found they likely to not fit under standard valve covers. I have seen a report that the HS setup great with no shims on an RHS head so perhaps the lack of fulcrum height adjustability is a non issue, stronger, more stable. One irritant, I see no reasonably priced tall valve covers for a magnum so I lean toward the nonadjustable HS.