HD SPRINGS

I'm looking at upgrading my rear springs on my 110, its had a tipper put on it and is used for tree work, its currently got the HD Britpart springs and they sag as soon as I put my chipper on, to be fair they have been on there a while. After looking around the height load rating springs I can find are the bearmach HD 130 springs which are rated to 510lbs. Will they fit ? I'd rather not put helper springs in or the help bags if I can avoid it. Thanks in advance