Hi Des,
Good discussion this is turning out to be, however.
I.
mate check out the fuel bulkhead as well, I hear these are quite heavy, see if you can remove that, or replace it with a reworked lightweight version,
the yankie 300SD's used a lightweight version of the fuel bulkhead.
being a racer I'm sure you don't need to be told that shedding weight = more power,
considered getting some lightweight panels from the US from the 300SD model?
considered drilling out weight from the chassis?
considered lexan? sp? for the windows?
need to send your 450 to Jenny Craig for a few months