Welding a nut on is definitely the better solution for the engine bolts/studs.
Today, I threaded the 10mm titanium stub for the rear brake reaction rod mounting, drilled and lightened the two 8mm associated bolts and also machined up the Mk2 titanium SA spindle.
Had a couple of incidents with the titanium this is the first which I simply blew out,
the second involved flames about 300mm above the lathe and required the extinguisher rather than the iphone for pretty snaps. The extinguisher was a powder one so had about an hour getting all the powder off the lathe.
I also spent hours applying release agent to the CF patterns (5 coats on each except the tank and the seat where I discovered small blemishes that require just one more skim filling).