Apparently the earth was flater back in the day and they just didn't make wide-range, close ratio, triple set ups. Actually what they would have done is called a half-step plus granny where you'd have something like a 50/44/28 in front with a 5 or 6 speed 14-28 freewheel in back. Then you doubleshift the closely spaced front rings to keep the ratios close and use the granny for hills. I don't particularly like that set-up as you end up using the granny ring a lot if you ride in hilly country. Of course if you go 14-32 or 14-34 with a 5 cog freewheel you humungous gaps so my compromise is to convert to a 7 speed 13-32 and run a normal 52/40 in front. If you really want a triple, there are vintage triples, they just aren't that common. If that Zeus crank is 144mm bcd then you could get a triplizer middle ring from TA and make it into a triple. You probably need a longer spindle for the bb. That's most likely what I would do.