Thanks for the knowledge Vincent. I have just started mine, with a bit of a different approach. I felt it might look odd with Plasticard over the shields (Different bulks, might be able to tell the difference from behind), and I couldn't shave down the shields enough to get it nice.
So my approach was, since the shields are round, just extend them with greenstuff downwards to look like the Khemri style shields. This also helps with the Coffin lids, as I think the thing that makes them stand out is the fact that the sides of the coffin lid angle inwards, rather than being straight.