Best 273 and 318 builds (NO 360's please)

I'd like to build a 360 but my 318 in the car runs so well that I don't know if I see the point
of throwing more money into a 360 build. The 318 holds 60psi at idle. Not a thing wrong with it except for it being bone stock. I'd like more punch. Any reccomendations?

It is a '71 Scamp. 318/904(with low gear set), electronic ignition with orange box and the only other notable mod is an Edelbrock Performer intake/600 Holley carb.

I think headers will give me the most bang for the buck. I still gotta decide what cam and possibly a head swap later. I'm gonna go with 3.55's later.