Step one, buy the books.

http://www.amazon.co.uk/Build-Your-O...ref=pd_sim_b_6

http://www.amazon.co.uk/Modify-Sport...9446388&sr=8-1

Just to add a bit to the advise, the Haynes set up is simple with upper and lower wishbone mounting points on a subframe that is incorporated in the final full chassis.
I am looking at taking the specs from the book to convert my Sierra backend Robin Hood to wishbones.
The Sierra diff comes in two LSD ratios, 3.6 and 3.9, Sierra diffs also have ratios from 3.14 to 4.7, you can use any crown wheel and pinion on a LSD diff internals, the Sierra LSD is viscous and may be a bit soft for racing, there are plate diffs and ATB's available to fit the Sierra case.
A friend of mine has converted a live axle chassis to DeDion, you use the original parallel trailing links to the DeDion tube with a panard rod, the Sierra diff and driveshafts.
The Sierra rear track is a bit wider than a live axle, I think about 4" total

Don't forget you can also use the granada diffs but you will need to extend the top left mount outward 17mm ( looking from the back of the diff) this will give you a few more options! Also I find the Granada LSD diffs are stronger and cost less.

Thanks guys, i'm not too fussy about diff ratios, but it must be LSD. I started with the original 3.09 in the atlas but changed last year to a 3.77 when i fitted a bigger turbo to compensate for the increase in lag. I have over 350 ftlbs and climbing so i dont notice too much difference.

A 3.6 or a 3.9 would be fine.

A dedion wont really fit as the centre of the tube has to sit behind the diff and my fuel tank is fairly close to the live axle as it is.
I guess i will have to look at getting a book. The reason i looked at the haynes was because the parts were easily accessible on ebay.

Is the Stylus like the Fury ie same track width? If so you are into chopping down the drive shafts as the Roadster uses them as per the sierra.

thanks for that, i did wonder if the stock shafts would be wider, i think i can get the shafts shortened, or new ones made but its an expense i could do with out. I was wondering whether an MX5 diff and shafts would be the right size. Of course that means using MX5 based uprights. I will have to look up some measurements.