How much compression you have? Compression ratio? Squish clearance? Timing? Ported at all?
If you have a good quality drag port on top of the factory castings, there may not be much you can really do. Bump timing up, raise compression, Nd some tuning.
If you are after some good low end grunt and midrange, sell the cub and try to get a serval or a small-block twister, or even a set of dune or mx port stock cylinders.
-jared