Roll bar on Sprint DHC

[Jem]

Hi,
I know there have been several rollbar posts, but I wondered if anyone found a similar issue.
I have a Rollbar and side bars from TTR that I am trying to fit to my Sprint DHC.
It fits perfectly onto the chassis bolts on the floor and I can see that I can get the upper mounts to line up with the points on the upper part of the chassis, but on the DHC, the rollbar rests against the fibreglass tray for the roof (see picture).

Grinding off the back of the threaded tube won't get it all the way down.

A spacer would probably work but I wondered what people had done and any photos of installations would be gratefully received.

thanks
Jem