148 would make it very early Rich, quite possibly putting it into 1969 along with Arno's Chronomatic. The hands look like third execution (the second execution has the same design but are only wide enough to cover the single hour markers, whereas those look a bit wider) so will have been replaced some time along the line - nothing to worry about, hands corrode and are replaced all the time. It would have originally had hands like those in Jan's example.

If it really is Cal 12 rather than 11 then that either means the movement has also been replaced or throws all the theories about how long the Cal 11 and 11i were in production into the nearest wastebin! That serial and movement combination would mean only a handful of months rather than the year or so we have been surmising...