beams motors have cam pulleys 5mm apart the gen 3 have the cam pulleys 25mm apart,
also have flat top pistons with a 33cc combustion chamber
gen 3 have a dome piston 10.4 to 1 and also have a 48cc combustion chamber
both motors have different valve angles beams you can put up to 14.5 mm of lift in them
the 3sge 3rd gen 12mm max
if i were you just keep the std motor as is unless you need a quad throttle inlet as i have 3 left and bolt up some black top throttles onto it and do a retune