Converting downstem shifters to barcons What considerations should be made for converting a downstem shifting system to barcons? Both the current system and the system that I would like are friction shifters.

The bike is a 1986 Peugeot Iseran 10-speed.

Thanks and be well.
According to the '86 Peugeot catalog you're dealing with stem shifters. You should have cable stops on the downtube. You will use those. Measure your handlebar inside diameter to ensure you can find barcons that will fit. If it's not standardized, get a new handlebar.