What do you guys think of the speedmaster bare aluminum heads

why 5 why not 7 including bottom cut to start to address #3
margins and back cuts are important
radius on the ex valve?
valves- flat or dished
"pro flo" or other small stem valves
Magnum valves?
Lots of LS valves in the correct or longer lengths in addition the the usual SBC
bead or square keepers
10 degree?
plan ahead