I have a 468 in my 68 convertible but I'm not making nearly the power you are.

You didn't ask a specific question so I will just share a little. I found I had fuel starvation issue trying to use the stock 3/8 line. I'm putting in a 1/2 line with RobbMc sending unit. I'm finding it to be a huge PITA to put the 1/2 line in. I could have went with an electric pump but I tend to like the mechanical.

The other thing that is a concern to me is the chassi flex with a convertible. Just driving down a smooth road in the feeling the gap between the door and rear 1/4 is just amazing how much it changes. I have the hotchkis sub frame connectors on my wish list. I do have the belly pan on.

It doesn't sound like you should have to much to worry about with a th400 and a 12bolt rear. Unless you put on some sticky tires and take it too the track. If you did plane to do some racing you might want to upgrade to 1350 joints and at least have a heavy duty sprag installed. my .02