Lots of choices... If you want or need to stay in budget, you can get a nice running stock looking 383. Compression around 9:1, no quench, iron heads, decent cam. Lots of fun to drive. Don't let me or others talk you out of it if that's right for your app. Care in piston choice and machine work will make it noticably stronger than original.

The next step up would be 440 source or Edelbrock heads. Next after that is a stroker.