Cinelli is a good brand and tends to be what all the retro guys go for although 3ttt, modolo, itm etc are all up there quality wise. Other brands are perfectly adequate ie SR but just not finished quite as well.
Regarding sizing I'd look for a 100mm stem and 42cm bars as they are the "average" set up. Old school sizing set the bar length so that the hub was in line with the bars as you looked down from resting on the hoods, bar width was the width of your shoulders. As I said though I'd start with 100mm and 42cm I'd probably also go with SR to retain originality.
I may have a stem or two plus some bars, I'll have a look when I sort out your leavers....which are the same as the picture of the bike in original condition.