Assuming it can handle it, the plan will be to rebuild the exhaust with a 100 cell sports cat – which will reduce MOT worries and hardly impact performance.
Welcome to 155 ownership.
Sounds a good car and overall nothing major from the assessment you have made.
I've just been through most of the restoration on mine, including painting it, but your list is similar to what mine went through.
Some pointers, if you are interested. The rear arch liners (plastic bits attaching to the boot floor) if fitted, allow moisture between them and the boot floor. Have those removed and the floor checked.
A 100 Cell cat will be very unlikely to pass MOT Emissions, especially on the 12V V6. I have a 200 cell cat fitted and on the 23rd of this month will find out if its man enough for the job (quietly confident as the car has been live mapped so not running rich anymore).
The rear compensator on mine was removed during the rear subframe restoration as it was found that the bracket that it mounts to which is welded to the subframe was too far gone. Anyways, no issues with braking hard even on curves. The rear calipers are just too weak to cause trouble imo.
If you need a recommendation on a paint shop, when you get to that point, give me a shout.