After adding more data, it doesn't seem to have helped much.
The other large galaxy is NGC1055, and the next smallest galaxy is NGC1072.
Details:
80subs @ 120s, 62subs @ 180s. Total 5.8hrs.
Gain 140
If anyone is interested only happy to hand over the data. hires:
https://www.astrobin.com/full/deind7/B/
Thanks for looking and advice always sought after :-)
PS: Thanks Fernando for the SGP book details.