Interesting geometry on the bikes ridden by the Crane brothers. The rear triangle has more racing bike length than touring bike (check out the gap between tyre and seat tube). That must have made for very close clearance between panniers and the riders heels - the Crane brothers are not short people.
From what I understand 753 tubing was not produced in Lengths suitable for touring geometry for many years. Tony Oliver built rough stuff machines in it but that might have been in MTB gauges and diameters or after a time when Reynolds decided to go ahead with ‘long tube’ production. However it seems it was never widely adopted. I bought a 753 Nigel Dean touring frame on this very forum on the strength of its rarity and even now it’s the only 753 tourer I have ever seen.