Thank goodness you're not thinking of putting those racing seats in the Augusta!
What engine and gearbox are you trying to split? If it's an Augusta, it sounds like you need to uncouple the clutch mechanism by pulling the operating lever out a bit. I have forgotten about Aprilia clutches, but there are plenty of people around who will know. The Augusta fuel gauge had a solid rod going forward from the gauge to the top of the tank on the saloon, but a flexible Bowden cable on the coupe, where the tank was at the rear. I have a spare fuel gauge from my saloon if you want it. I think an Aprilia engine in an Augusta would be great. I started doing just that many years ago, but ran out of funds before I got very far. I think the March cars had the normal instruments, the same as the convertible. Regards - and good luck with it, John