ok... turns out a seatpost that I think is 27.2 fit in perfectly into the bike Guess it wasn't 29.

thanks for the link on alloy cottered cranks, unworthy.
I thought all cottered cranks came with a big chainwheel attached. Would finding chainwheels for that be difficult? I guess it would be infinitely easier/cheaper to find an italian threaded bb and crank instead.

Any conceivable chance that a 1960s or 1970s Olmo does not have an italian threaded BB?