Re:
Worth noting (more in passing as it's not strictly relevant to the OPs problem) that the Campag BBs of that era were not true ISO - the tapers themselves are a fraction longer than a true ISO so you have to be careful about mounting 1049s to a straight ISO BB, especially if you think they have been spread - as you can end up with (especially the LH) crank migrating so far up the taper that it comes up against the scalloped shoulder of the taper - we've seen plenty of vintage cranks crack due to this problem, including one of my own, I'm sorry to say :-(
For a short while in the fixie-hipster boom a few years ago we also had a succession of the current Pista cranks coming in to us cracked, having been fitted to 111 ISO BBs because the Campag Pista BB is not well enough sealed for road use (naturally, that's not what it was made for) ...
I think if the tapers *have* been spread to that point in this case there's a danger of the fixing bolt bottoming out anyway - looked at logically, there would normally be something of the order of a couple of mm clearance on a non-indented stay between inner ring and chainstay and the axle should come through the crank, post tightening down to within ~3 mm of the base of the crank bolt recess - so if the crank is migrating up the taper to the extent it appears to be, bottom-out is a risk.
I'd be tempted to strip everything out of the frame and do a dry assembly of the crank to the BB axle off the bike and have a look from the back to see how far up the taper the crank is coming, check to see how close you are to bottoming out when the crank bolt is undone then figure out what to do from there.
It's likely teaching gran'ma to suck eggs, I know, but given that the BB axle is assymetrical, you do have the axle in the BB the right way round? Stranger things have happened!
Depending on which "fixed" BB cup you have in, there were both thick-wall and thin-wall variations for some years - you could possibly use a thin wall if you can lay your hand on one and that's not what's in there already ...
I've got a Royce 119 mm BB in one of my vintage bikes with a 1049 chainset to get around a broadly similar issue - the chainline isn't *great* but like the OP I was wary of squeezing an indent into the chainstay (I am a framebuilder and still didn't fancy the risk!) so that may be an option you might want to look at. It depends how determined you are to stay "all original".
You'd have to hunt around but OMAS, Rino and I think Galli all did BBs with adjustable chainline back in the day, all of which, IIRC, worked OK with 1049 cranks - so one of them might provide an option too.