Re:
What amazing condition that is in.
I'd say mid to late late 70's, which was long before Dave started making his own frames. I have two of his early frames, one that I think comes from around 1975 and one from around 1978, the 78 is fully restored and the 75 will most likely become a run around at some point. The cranks will more than likely have a year of manufacture stamp on them, a quick google will tell you what to look for.
Dave was always big on Campag, so you could look at using age related parts all from them, or more correctly for that age of bike a mix of quality parts from various manufacturers, which is how my 78 'clubman's' Lloyd is set up.
The EO symbol will be the manufacturer of the bottom bracket casting, hopefully one of the knowledge fonts will be along to tell us who made it.
Fantastic find, well done for the rescue job.