If you import all of your options into a “single line text” field as 750 different records, you can then convert your field to a “single select“ field afterwards, and it will convert your records into the single select options.
However, 750 options is a lot of options. You may want to consider keeping your options as individual records in their own table, and then using a linked record field instead of a single select field to select the appropriate option.
nice trick that converts single line text to single selection. But sadly, it doesn’t recognize all fields as unique. The 750 fields were only separated into 3.
In the other way you proposed it´s actualli the better. But I think I need to configured the integration through single or multiply select first. And then via automation linking the record. So I think that I both cases I will need to find the way of add the 750 record to the “multiple select”
Please let know if I´am understanding correctly