1 hp/ci is quite respectable... How much CR and what cam? You will get more power with a leaner mix around 13.5:1 you don't want to go much leaner than that. Maybe can stand more timing lead... The plugs will tell you... Look for the heat line on the ground strap, you want it about the middle of the bend or a little further... More lead pushes the blue line further down the strap to the base... That's too far. What fuel are you running? With a little tuning you could see a couple dozen more horses... What do you have for intake and exhaust?

-Chris