looking to rebuild my 340

It's a 40 year old motor it might need to be bored just be prepared for that.
This is a thread by MRL that the 340 motor made 470 HP and 410(?) TQ. Sounds like it might be what you're after. Like MRL motor, mine is also a hyd roller cam with eddy closed chamber heads. His cam is a tad smaller than mine (mine is @ 50, 231/239 .535"/.550") but mine is 30 over and his block was 40 over.