I think MP puts the old 509 in the 410/6pack crate motors.

Recently put together a 410 with a custom engle grind from
Jeff Patterson (rapid340) and it works great, but it's a solid
247/253. Has a nice chop at idle,smooths out at 1500 and pulls
hard to 6k.

I'm sure it would pull past 6k but I have a TKO-600 and I don't
want to shift higher than that. Mike