All I can contribute is I was so impressed with Dulcichs 452 porting article that I am going to duplicate it (as best I can/no flowbench) as I have a set of bare 452's. It does take new 2.14/1.81 valves/new guides & checking/milling them flat (intake side also). I have a valve grinder. pushing me in that direction is I have some plateau pistons already, oh & you need to mill the open chambers flat/equal. I will (likely) sell my 915's (2.08/1.74 with new valves/guides, I need to finish the valve job) to recoup some money. Stealths might be the way to go, the alum saves weight, iirc there was an extensive thread on alum vs iron & the concensus was that there is no magic in alum but it does wick away heat faster & that lets you run a higher SCR/DCR tho heat is power so I'm wondering does the power bennie from the higher psi get negated from the heat loss ??? and is alum just a way to deal with a too high of psi that iron heads cant handle. reportedly stealths need the retainers/locks replaced and the guide clearance checked. maybe the big bennie of the stealths is a better bowl/port shape & I have no doubt it is significantly better, how much I dont know but I do have a set of bare super stealths on the shelf (plus their valves/required offsett (intake) rocker assys with the dreaded needle roller rockers. Just thinking out loud here and a BTT for ya since you werent getting any love on this Q