The wonderful MG Midget Challenge is still going strong as a race series in the UK, with various classes depending on modifications. Recently it has joined with the Austin Healey Sprite Series (see: www.mgmidgetchallenge.co.uk).
Anyway, here is some info on race preparation from 30 years ago for the least modified class of this race series. Extracts from the much missed CCC (Cars & Car Conversions) Magazine, with the staff writer and racer Art Markus who built and raced a car in the MG Challenge and wrote about it at the time. Some of the parts prices and permitted modifiations and commonly used parts make for interesting reading (e.g. 4.5 inch wide Rostyle wheels commonly used and 5 inch rims not allowed).
Part 1 - The shell (Dec 1985, 3 pages)
Part 2 - brakes & suspension (Jan 1986, 3 pages)