6’ 3” in an S3?

[Youds7]

Hi everyone this is my first post on the forum. 

I've been looking to buy a 7 for a while and have found one that ticks all the boxes, well almost! There is just one problem. My 27 ear old son would like to drive it occasionally but it's an S3 and he's 6' 3". 
With the drivers seat all the way back the cockpit is still a little too short for him. The vendor suggested replacing the leather seat with a moulded one?

Anyone have any experience of doing this? or any other tips would be appreciated.
I'm not sure if it has an adjustable pedal box (I'll check with the vendor) and it has a 10" removable wheel.