Identification on used Mopar Crate 360
http://www.forabodiesonly.com/mopar/archive/index.php/t-5312.html
380 HP P5249499
390 HP P5007646
There's also a 410 Magnum crate motor kicking around out there at a pricey 10K.
I have the 380 version and I would recommend getting it if the price is right. Bought mine NOS sitting in a barn for my 73 Duster. I put no more than 20 hours on it and never maxed it out yet. It is mean and nasty!
I believe the heads were upgraded to the higher HP versions.