340 to go faster.

G'day All,
Just rebuilt the 83/4 diff the other day. Was a LSD but only 1 wheel was spinning, great now. Anyway I was talking to the bloke who did the diff & told him the 340 in my Demon is putting out around 350hp at the flywheel. I asked him how I could get another 100hp out of the motor without going crazy on $.
He simply said for about $2,500 aus drive in & out he'd do a cam upgrade, aluminium intake & extractors.
Don't really want to change the originality of the engine bay but I guess I can bolt the factory intake & headers back in the car later on if I like.
Getting used to the hp, but want more.
Had a 1970 falcon GT years ago & that had 450hp & man did I love the speed.
Anyway what do you think?

Cheers,
Glenn.