I received a lump sum payment for a pension from working on a foreign country 20 years ago.They deducted 45% for taxes so I would like to declare this

The section on pensions asks for a 1099-R which I don’t  have.  Instead I’m thinking I would enter this as foreign income and then get a foreign tax credit. Not sure if this makes sense because I haven’t work there for 20 but I don’t see any other way to do this