For what its worth I think the car looks better with your 'photo edit' skills.
The natural proportions in life are 1/3 - 2/3rds and the original design ignored theses.
the rear bit to cur off the hump and move the seat back are straight forward, cutting the chassis and re-welding are the basics and again can be achieved easily either professionally or in your usual well equipped and experienced workshop.
The problem comes when you considerer the bit you did not mention.... the extension of the bonnet and the reduction of the scuttle this is more involved.
Getting the strength into the underside of the bonnet as it overlaps the scuttle and sitting smooth would be where I see the challenge.
If you had the original moulds its better but to mod the bonnet and make a mould then cast the new proper bonnet is a labour of love, time and money.
Everything is possible but you have to ask is it worth the effort to do it just to say you have. Just go and buy a 350Z and enjoy the comfort and thrill of a production car that works.
Then drive it, not spend 10 years building it, never to drive it.
Well you did ask.......