I have used a bunch of the 454's. You can't build them for the cost. Forged bottom ends and a hydraulic roller. Put a one inch open spacer on the stock manifold, 34 deg timing advance, and with a 750 holley vac secondary they'll make 440hp. One customer has a pair in a 38' donzi they've got about 250 hours on them so far. No reversion issues with stock cam, and they come with brass freeze plugs and a fuel pump boss..