I replaced mine a while ago without removing the turbo or any of the exhaust/manifold. Unfortunately it wasn't a conversion, so things may be different. I also can't remember how I did it, but I remember extensions, small spanners and hands, undoing the bolt from underneath and then some serious wiggling to get the starter out from above.
Absolutely no help at all I know, but just to say it is worth trying it without disassembling anything.