It sounds like a lot of trouble to go to for a bike which is working already and which you only ride a couple of times a year.

If you do decide to go ahead I would strongly suggest that you ensure that the shifters are working 100%; repairing Shimano brifters is not a sure thing. You also seem unsure of the exact configuration of either the brifters or the chainwheels; this sounds like a shaky foundation for a project you will be doing during an overseas vacation.

"Never Fix A Running Piece" may apply here.