I have a 48-38-28 chainwheel and I wonder if Shimano 600EX Arabesque has enough leeway to accommodate it. If you know another derailleur from the same era that could do it that would be also useful to me.
Usually racing front derailleurs like an arabesque will not allow the extra tolerance for a third ring. With that being said, the only way to know for sure is to try it.
One thing to keep in mind is that the spindle length on your bottom bracket affects this as well. While your derailleur may have the extra tolerance to fudge it in some cases, if your spindle is longer than shorter, then it may push your crank too far out for your fd to reach, even with the limit screws taken completely out.
To try it, just throw the crank and fd on. Take some bare cable and attach to the fd so that you can pull it with your hand. Take the two limit screws all the way out and manually induce pull so that the cage moves all the way out, to check for the large ring. Then just see if letting go all the way will shift back down into the small ring.
Generally, I'd say it won't work... trust me, I've thought of the same thing before. I always end up finding another 28.6mm clamp fd that was meant to support three rings.
A road triple will work. I run a shimano 600 arabesque drive train, chainrings 52-45-38 .28-13 7 speed cassette,double front der,short cage rear der.to make it work I use a 117.5x68 bb spindle and set the chainline up using the middle chainring and the middle cassette cog this setup works very nicely in the coast mtns where I live. When I ride in the Sierra mtns I switch the cassette to a 32-14 7 speed with a long cage rear der.I limit the cassette setup to a 7 speed as any more cogs on the rear you are limited in gear selection by chain crossover.