Since you already have the 305, just slip a decent cam in it, keeping in mind a torque cam will be better in the engines effective rpm range. use an Edelbrock Performer or Performer RPM intake, or even just a clean beadblasted H.O 305 intake. add some shorty headers, paint it up pretty with some nice chrome or aluminum accessories and run it! Like was said earlier, it will get you going and if it stays nice you can sell it later when you swap in the powerhouse!!