Most of the 105 was salvaged from the original bike which had a full gruppo including headset, bb, pedals, hubs.... still have all the parts stored in garage.
Parts were totally stripped, every nut, bolt and spring removed and de-greased then rebuilt unless it was too shabby, the powder coat finish on the chainset was shot and I had to drill out the bb.
NOS parts were:
Shimano FC 1055 chainset £50 eBay
BL hoods £10 (orginals were white, could only find black on web)
3ttt Bars and Stem £10 each from Planet X
Cassette: £18 Planet X
Chain: £8 Planet X
Wheels were custom built to get the retro look.