Yes, there seems to be a contradiction indeed. Will have to check against drawings of the real one to determine which is the correct view!

The firewall needs to be repositioned but seems it can easily be done.

A build article in RCSI mentions 12.25 Lb and a 90 two stroke and no problem balancing, but he changed the rear fuse from 3/32 to 1/16 planking.

Lots of potential for lightening certainly. It's an old design, but a good basis for improvement.