you always stand the chance of floating a valve with hydraulic lifters if your wanting to turn it up (high rpm) as a drag car.....i personally have floated them on the street ( back in the day)..
if you are going to be seeing more street use then strip then hydraulic roller hands down ( IMO)..If its gonna be drag only ..OR you plan on turning it up (rpm) then go the other way....
oh yeah..i got a solid flat tappet in a 406ci....about a 520 lift...very quick..lots of bottom end.
also remember if you go solid flat tappet you need to break in cam the old school way.......( imo)
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "