From the 318 experience I have had, if I was starting fresh with a mid 70s 318 I would look at the following if bolt ons are what the limitation is. At least that's how I read the question.
1) LD4B intake
2) 650 Holley double pumper
3) Headers
4) 2.5" dual exhaust
5) Summit K6901 cam
6) Matching valve springs
7) FBO ignition
8) FBO limiter plate in stock distributor
9) Mini starter
10) Sweet M/T valve covers cause I couldn't think of anything else.
Now I say this because when I think "Bolt on" I think you leave the block and heads stock. But that's just me.
Cley