[Dominik]

I think a BB only appears front heavy because of the smaller tires in front, tending to understeer. A typical compact 3-cyl car nowadays has the same weight on the front axle as a Cobra, but only 30% on the rear. Not like 50/50 of a Cobra.

If all fails, and the cast iron puts you off, use aluminium engine (parts).

I don't know how low you get get in weight for a BDR, but my RAM sat at 917 kg with room for improvement.