I'd agree with the advice from Calum & Genocache, with the safety net of taking out, if it didn't already exist, membership of a roadside recovery organisation.
If you want to be really safety first, do the first 50 miles going 25 in the wrong direction (away from home), drive the next 25 back to the restorer so he can cast his experienced eye and ear over it. My numbers aren't meant to be precise, merely stated to illustrate the principle. If 50 miles is too much for you, reduce to 25 or 30, but make it more than a spin round the block.
Point out to him that he is then assured of the quality of workmanship of the person who did the 1st run check (himself).
It might not be pleasing to read, but his concern may not be that his workmanship is not up to scratch, but that he thinks the drivers (your) analytical skill is 'unproven', so an unnoticed simple problem may be left to become severe.
I have done something similar, finishing the rebuild of a MGB engine the day before I was to drive 220 miles to South Wales.
The early life failure was a thermostat stuck closed, noticed within 2 miles of home. Immediate return to home, new thermostat, and I was on my way again. The interesting bit was a DSJ inspired valve clearance check in a tree shaded layby on the way home.
Have fun.