[undy]

You really need a matched rotating assembly, crank, rods and pistons. The BB Chevy rods won't work on your stock 390 crank. Even if they would you have insufficient stroke to reach 427 ci. Your cast iron heads will accept a bit larger valves but the improvement will be minimal, maybe not worth the $$. I would go to a hydraulic roller, not a hydraulic flat tappet. That will yield more HP and eliminate the lifters takin out the cam problem. Remember, with any cam change you'll need to revisit if the valve springs need to be changed. Don't cheap-seat the rebuild. It'll come back to haunt you.