I agree with the 4.25 crank route. Put a 4.25 crank in it, use pistons that give you 9.5 compression with the heads you pick and go with a modest camshaft that matches how you are going to drive the car. I'd use Trick Flow 240 heads on an engine like that but Edelbrocks or Stealth heads can also be made to work.
From the 440Source.com web site, a 78cc Trickflow 240 heads will result in a compression ratio around 10.3.
With the aluminum heads and moderate cam, I think that will run just fine on pump premium gas.
