[Nonfractal]

Rob, 
if you are looking to  make a  competitive track car you have 2 main options for a chassis. 

1. The modern way is a made to measure 3d chassis 
https://www.shapeways.com/product/KG2PZ4...911-inline
These can sometimes be sourced in Europe which lowers the postage cost

2. The old school way is an adaptable chassis like the slot.it HRS2. 
http://mre.co.uk/catalogue/slot-it-hrs2-...06495.html
Using hrs2 is a bit more work because the body is not typically mounted by the body posts. 
The link above is the complete hrs2 kit but you can buy just the chassis and use your own running gear.
My entry to this year's winter rally proxy was HRS2 based.

The old-old school way is to use a brass chassis. 
I'm afraid I don't have any experience on brass chassis construction. 

Alan