OK figured out a work-around for the sills (or rather lack of them):
Oh, and mounted the boot lock.
- Cut back the sills to match into existing wings and doors. This involved removing the lower 65mm or so and just leaving the curve and top fixing
- These are fitted in place (complete with cock-up on N/S which I need to glass in)
- Have stainless steel cover plates made up to set behind the GRP and bend around underneath the Z3 inner sill (been quoted just under £100 the pair
- The cover plates will be bolted behind the GRP out of sight with countersunk bolts on the lower angled part
Oh, and mounted the boot lock.