Make a cardboard seat from the plans in the book and see what its like to sit in the car.
I have driven Adrians car and spuds too and I hope they both forgive me for the statement I am about to make, Adrian's is subtle and like a fine wine to be made the most of, Spuds is like a harsh whisky,the kid who has been thrown out of school for being the hooligan but with a purpose and it fullfills that purpose as does Adrian's .
I am 6" 2in and 18 stone with a 48 in chest and get in no probs but not in spuds seat comfortably,again its horses for courses and fit perfectly in Adrian's.
The idea of fitting the shafts to the wrong side was to allow for adjustment in the tunnel placement and move the diff across slightly.
I had thought about the left hand nut problem and swapping the joint ends around should fix that,nothing is impossible just more work
There is approx 450 mm between the chassis rails in the seat area.