I have treated myself to a new set of seats but the fixing points are different. When I built the car I strengthened the floor with two steel T sections about 25mm high across each side. To overcome this I made some ally packers for the seat to sit on which also helped to stengthen the floor front to back. Now these supports are in the wrong place.. I need to mount the seat further back so I am bolting either side of the T section instead of in between the two T sections. I want to spread the load to the floor so was thinking of spinning up so nylon spacers 25mm thick 50mm diameter for the top and 5mm thick for the bottom. I am trying to keep the cost down so trying to avoid making some different ally blocks.

Thoughts?

A couple of pictures / drawings would help, but could you run a top hat section length ways between the two cross braces to bolt the seat to?