[Berlinista]

thats cool. Consider however that there are some major differences in the inner body too, such as the lower radiator support, floorpans, firewall, etc. If it doesn't have to be original anyway, keep the hanging pedals, replace the lower rad support by a piece of roll cage tubing (easy engine in/out and maintenance and less chance for rot!- also far stronger than standard, so less trouble when you have a stiffer stabiliser bar!)
Will it have a roll cage?
Think about strenghtening the area from the front suspension towards the stabiliser location, which is a known problem here in race cars with poly or alu wings. What happens is that this area flexes instead of the stabiliser bar actually working.
Also realise that the dashboard area is different than that of a stepnose so before installing the dash, check out first.
Perhaps you can modify the floors too so that the whole 'italian ape 'seating can be prevented. I once completely lowered a floor for an over 2 metre long race driver.
The holes for the steering houses were also adapted. You keep the front one standard and redrill the others. This way you can lower the steering arm, which is necessary if you lengthen the arm so the driver can sit further back. Otherwise the steering wheel would be too high up. An inch is possible no problem. Which is sufficient inside. You can then create a 20 cm longer steering arm.
And that is cool.
Great project, I'll follow!
Rik