The plans call for the suspension block to be 5.". "If" you made it 6.", your fine, but if you made it 2." over, that would mean your suspension block is 7." and it's to wide.
It shouldn't be a huge hassle to make it smaller unless you welded the hell out of the rack mount. If you did weld the hell out of the rack mount, it's still doable, it will just take 20 minutes or so longer, that's all.
Do you have access to a bandsaw that has a metal, blade on it?
If so, just cut it down the middle and remove the extra 1.". After it's cut in half, ... remove the rack mount pieces off both sides and then weld the suspension block all back together. Get a new rack mount and set it inside and weld it in.
Your done.
Bill