The seat is easy to make, I can send dimensions;
The tank will be a challenge, they are hard to find and expensive. A 6 quart Briggs tank can work as temporary substitute;
The brake caliper is the same on all Tote Gote Nova models, but will still be hard to find. I have dimensional drawings of all the caliper parts.
It is possible to use a Comet 20 clutch with Comet 200836 spacers to fit the wider belt. The original Climbaway clutch is hard to find and expensive.
The original belt is a Jason 1522V270, 15/16" wide X 27" long.
It appears you don't have the original 7hp Briggs motor. What size is your motor shaft?