GA aircraft, especially elderly ones, are all individual; you rarely find two with exactly the same fit and layout. In these situations I find a “custom” checklist totally reasonable. My own, 1960 aircraft, has a glass cockpit. I started with the manufacturer’s checklist, added the checklists for each added bit of gizmo, then sorted into a “flow” and sensible sections. Nothing is missed put that should be there and the new bits are in places that make sense.
Once things get bigger the layouts are similar, if not identical, and a standard checklist makes total sense with multiple crews who may each work with other people at any time. For a private owner, single pilot, you can make it work for YOU.