The only 400 Ford I can think of is the 400 M, which was a sister of the 351 M engine. If that is it, they weren't bad engines (had one in a T bird) but were not designed to be performance engines, but rather to haul big cars around. Not much speed equipment, but I think normal stuff like intakes and cams are available.

For a street driven rod one would be fine, and they look somewhat 351 cleveland-ish.

Don