Cheers. It was easier than I thought. I had a couple of Mk2 round light buckets, one was steel and the other plastic but it was almost exactly the same as the steel one. I've got another set on my other project and they are completely different again and seem to be less suitable for the conversion.
I've basically dummy fit the blanking plates making sure they were central to the grill and used them as a template to trim the front panel to allow the buckets to fit.

Cleaned up the buckets removing the bits that hold the mk2 grill and screwed it to the plates. For now I've riveted the plates to the front panel but will probably weld it in later. This is the first time I've done this and figured rivets were easier to undo than welds incase I got the positioning wrong.
