Deanno,
my understanding (from a previous post) is that the roll bar per say is not an IVA requirement. Search the IVA manual for roll bar or an equivalent and there is nothing about it. So fabricated (i.e. not bent) roll bars maybe OK.
The aspect of the roll bar that will be inspected is the use of it to secure the seatbelts/harnesses. For this purpose the IVA inspector will need to deem it suitable, but this might only concern the fixing of the roll bar to the chassis (see below) and the suitablitiy of the cross bar to which the harnesses are secured. I see you don't have a cross bar at the moment but presume you will fit one. Puting all this to gether my interreptation would be that: if the roll bar is adequately fixed to the chassis and the cross bar mounting the harnesses is suitalbe then the top of the roll bar shouldn't matter to much, assuming no sharpe corners blah, blah...
One thing to note, and a little mod. I have to do to my fabricated parts for the back stay lower mounts, is that AshG failed when having only a single bolt, it looks like you have too (correct me if I'm wrong). So I am planning on having two fasteners per roll bar backstay.
See Ash's note on his IVA fail here:
http://www.haynes.co.uk/forums/showthread.php?t=3700
This maybe a bit discretionary on ther part of the examiner, but my take is it's best to err on the safe side rather than have to re-work it latter.
Hope that helps,
PS: Looks like davidimurry and I were replying at the same time, sorry to covers some of the same ground!