Yeah, It's got a hemi.

58 was the last year for the early Hemi, so this is a transplant done at some point in time. That motor is probably worth at least half of what the price of the car is; if it were rebuilt, at least $6 to $7000. It appears to be the single 4 392 - rated at 345HP. Rebuild parts are available for it through Hot Heads and other places. I've got a completely rebuild (with some modifications) single 4 392 sitting on the stand waiting for the right project to come along.

Edit - early Hemi's were available in Chryslers 331, 354, & 392), Dodges (241, 270, 315 and 325)and DeSotos (271, 291 and 341). Parts interchange only within each family.