OS 120 III is surely the best way to go and if you built it light and correctly you will not need any lead weight at all on the nose.

My TF P-40 glassed and painted, with operational flaps and Robart retracts weighted 5 kgs.

However, remember that it is not an every week flying warbird. It's hard aerodynamics combined with it's only 1,6 m wingspan and the problematic Robart rotating retracts will surely will not reward your efforts. The look however is one of a kind. I built mine because my daughter loved it

Here are some pictures of it:

Stelios