454C10 i think got confused as we both were commenting on a 305 motor the other day, the LO3 is a 305 and the LO5 is a 350.
to be honest i dont care for the cam you have chosen, it has an extemely aggressive ramp rate for a hyd flat tappet cam. i would be very weary of wiping out the cam with that aggressive of a ramp rate.
if i had to guess then i would say that you are in the 1hp/cube range. the factory dished pistons are what is acutally hurting you since you are acutally loosing power due to there not being a propper quench pad. if you where to have gone with a 12cc dished piston like the ones from KeithBlack and the factory 64cc vortec chambered heads you would likely be in the 380ish hp range