Mike,

Try contacting Sergio (Serge) at:

Merc-Talk
Unit 4/23 Aylesbury Street
Botany NSW 2019

Ph: (02) 9316 7303

It is not specifically a performance shop, but Serge is fairly knowledgeable. (No affiliation, just a satisfied customer).

Personally, I don't think that going naturally aspirated route will yield you much in terms of HP per $. Even when you take account the funds required to rebuild and strengthen the engine in preparation for forced induction, I think you will find that the HP per $ factor is still in favour of forced induction.

Hope this helps.

__________________
Klaus Langbein
1985 380SE (W126)