Roll bar height too

[DaveyB]

After roughly positioning my seats and mocking up position of roll bar my head seems close to the top of it too.Instead of butt welding same size bar to bottom to increase height I thought about boring some sleeves out of bdms bar making them same thickness and getting a good fit round the roll bar and welding on the inside and the outside to give me the extra height. And perhaps making the rb1 plates a bit thicker.
What are people's thoughts?

Thanks
Daveyb