Looking at the photos Rat,i'd be inclined to re build the bottom 300mm or so out of some .6 or .8 zincaneal sheet,i've done it several times with good success and very little bog(i'm no panel beater)and a bit of stuffing around.The front of the guards look good and this is the problem area if damaged or rusty.Good B10 guards are as rare as rocking horse manure and cost a motza if you can find any.
Another option is to get a pair of glass guards,there was some one on this site looking at them some time ago,a bit of research and questioning should give a result but i remember thinking at the time they where not cheap.