Bucket seat track extenders for '63?
 

I recently bought a '63 LeMans convertible, which is on its way to our home from WI. I may need to move the drivers bucket back a couple inches or so. I see various seat track extenders on supplier websites and ebay, but they're fairly generic and designed, for example, for GM "66 to 72 A Body". One vendor advised me they should work fine as long as the floorpan is flat. Has anyone used or fabricated this sort of thing? Thanks

Buckets are on 4 raised mounting plates each. Easy enough to extend these plates and remount.