[Bill D]

Rune
To get 390 HP from a 289, you're going to have to run high compression (11:1 or higher), a solid cam, and some good heads. The crank and rods are going to have to be forged steel and the pistons forged aluminum.

A cheaper way is to build a 331 (bored and stroked 302) and just tell people it's a 289. They both use the same basic block.