Going back to the cottered crank might require you to be young and strong. Mine was a 50/47 in front and a 14-22 or perhaps 14-24 in back shifted by a Gran sport rear. Keeping gearing like that, your shifting will be fine, but I had poor luck with easier gearing.
I have seen 49/46 front also, and I am told the 116bcd three arm crank can accept something in the mid 30 tooth range, but I’m not sure how available they are. I did search a bit in the past with no luck. The crank arm also has to be compatible too. Nice project for you.