If your crank grinder knows what he is doing, there is no way I would worry about it. I have a 451 with a ground 440 forged crank. Never had it hardened. Made 620 HP and drove around in a 71 Road Runner. Tore it down and inspected the bearings. Put it back together a little differently and made maybe 100 dyno runs from 700-780 HP. Tore it back down and de-tuned it to 580 HP and installed it in the shop truck. Still has 40 psi oil pressure at idle and 70 psi at rpm. I'm thinkin' you'll be okay.
