I've re-sized and refitted the padding on the primary seat panel and cut the piece which will provide a degree of 'bucket-seatness'. I will cover this in firm foam which will be my next task. Hopefully it will work out.
Bucket seat piece:

Chamfered to facilitate easier foam application:

Location of section with re-sized main panel:


Bucket seat piece:

Chamfered to facilitate easier foam application:

Location of section with re-sized main panel:

