Hi Fred,
Like many other owners I have adopted most of the modifications you mention apart from the polarity change. The reason I am still +ve ground is that I have an electronic conversion in my fuel pump and I am still using the original +ve ground radio. The gauges and the clock are not polarity sensitive.
Fitting front discs was my most recent mod and I am very pleased with it. I had already fitted a servo (1:1.9 ratio)and had found the drum brakes a bit sharp, but this has disappeared since fitting the discs.
The higher final drive ratio was my very first mod - I fitted a 4.3:1 diff from an MGA which was a direct swap into the Magnette - no complications with the half-shaft splines, and I found it a worthwhile improvement. In my opinion, if you are retaining the 1489cc engine this is about as steep a final drive you will want, but it is a matter of opinion and depends on what sort of performance you expect. All you need to know can be found Here:
www.zmagnettetech.info/modifications/rea...of-final-drive-ratio.
I have also fitted the Hi-Gear 5-speed conversion and can recommend it.
Subsequently I fitted an MGB 1800 (3-Main) engine and have acquired a 3.9:1 MGB banjo diff but have yet to try it. I may not bother as the combination of the 4.3 diff and the 5-speed box gives me almost all I want.
In case you haven't found them yet, you should have a look at the bulletin boards here:
www2.mg-cars.org.uk/cgi-bin/gen5?runprog...102100099&mode=slist
And here:
www.mgexp.com/phorum/list.php?27
Any further questions, feel free to ask.
Regards,
Andy Dear