I've done this a few times and consider them the most interesting builds. Don't get me wrong, I love a Pinarello Montello with full Record, etc, but they get a bit boring - there are no details/differences to spot with these show bikes - all full groupsets and SLX tubing.
This white one here is one of my favourite bikes, despite being one of the least glamourous.
Bought a tatty red Olmo, got it powder-coated (plus a couple of clear coats over the decals), then added what I had in the workshop. Mainly 8-speed Shimano 105, except Dura Ace rear mech; Campagnolo Chorus chainset; Tifosi carbon shell BB (can be seen through the slots on the underside of the BB shell); Mavic SSC d/t shifters and some 1050 non-aero brake levers (these feel tiny in your hands compared to aero levers and especially brifters).
The wheels are almost NOS, though the tyres have been changed, as I can't trust 20+ year-old 20mm gum walls!