318 to 390 hp?

With 390 cubes and good heads it should be pretty easy to get to around 400 HP. Alot of 400 HP builds out there on just 318 cubes with good heads. You can approach 300 with a mild build and small valve heads. Your 390 will be able to use a much larger cam and still be very street friendly. I know there are members here running that combo, hopefully they will chime in and can give you some specific HP numbers they see with their combos.