you need to get a bolt with a countersunk head make sure it has got the same tensile strength or higher than the original one, then I found a large diameter plate washer which was about three to four mm thick and countersink this so the new bolt sits flush.

you could just countersink the bush back plate but I didn't want to risk this because it is not thick enough and would probably weaken the fixing, to be quit honest I wish I had got mine from Motorsport developments it would of saved a lot of time and hassle, the only reason I got the GGR mount is because I was passing that way and wanted to lighten my wallet a bit "the last sentence is a lie because I stuck it on my Visa and increased my Debt some more

I have got some pics somewhere will find them if you want?