I would change the cam for something a lot smaller because of the car (weight) and altitude and modest 9.3:1 compression ratio.
Something around 212 to 218@.050"
The S/R heads have modest flow in out of the box form Not much different from a stock GM 76cc head. Porting could fix that.
Why not ditch the EFI and supercharge it? Will more than make up for the lost power caused by the high altitude. If you happen to take a trip out of the clouds, carry a low boost supercharger pulley with ya to adjust the effective cylinder compression at the lower altitude.
A Weiand 177 pro street blower would rock on this motor.
Or keep the EFI and turbocharge it. You're a prime candidate for one of these rear mounted turbos.