Vintage dress alteration dilemma

This incredible dress came from a bursting at the seams vintage thrift store in Brooklyn that sadly closed down last year. It is a heavier weight textured cotton with azure blue background and white almost peony like flowers delineated in purple. It's very fitted with an empire bodice and a slight A line to the skirt. It has wide set shoulder straps and beautiful scooped back and on me hits a couple of inches above the ankle, though was possibly intended as a maxi. (60s designers were not very accommodating of the taller, big-footed lady I find.) 

I got this and a beautiful Mexican cotton pleated maxi skirt for $25 in their closing sale.  

$25 for BOTH!

That is without a doubt the best bargain I have ever found (aside from the $50 necklace I bought the other day for $2 because it had the wrong price tag on it.)

I am a totally useless sale / bargain shopper. I'll walk into a store that has a sale on and walk out with something I don't need and wasn't on sale.  I don't have the patience to rifle through endless racks of sales tat on the off chance I might find a gem.

I'm not sure what it says about me but I prefer shopping in an environment where the presentation of the clothes has been thought about and care been taken to show them at their best, where I can find my size easily and I'm not fighting to disentangle the thing I want to look at from the 18 other things that also seem to be attached to its hanger.

I know a more rarified shopping environment is accompanied by a more toppy price tag, but aesthetics are important to me - that is Reason No. 83 why I sew - and that extends to the whole shopping experience too. I'm clearly not talking Chanel here but the amount of times I've walked into a branch of a lower end high street chain and walked straight back out when faced with the standard jumble sale of crackling polyester means I don't even bother any more.

I know thrift and vintage stores are different to your average high street chain store, for ethical reasons amongst others, and I used to frequent them and the old Rag Market a lot when I was a student in Birmingham, but I still have to consciously summon up the wherewithal to push through the doors and deal with the chaos.  So, that is a long way of saying it was relatively unusual for me to be in a thrift store AND to score such bargains.

Which can only mean that this dress and I were meant for each other. 

However, that's where we get to the point of this post: the only downside to this whole escapade is that I can't do this dress up all the way. I really couldn't leave it behind, but I haven't been able to wear it as I can't think of a way to make it wearable.  

It isn't disastrous, on me (rather than the dress form) there is only about an inch and a half that doesn't meet, but I'm having the hardest time working out what I can do to make it close. 

There is a fairly generous seam allowance (5/8 inch) and I could steal a little from each side seam in the bodice. In addition there is a built in bra affair which I'm toying with taking out. It's disintegrating and in pretty poor shape, isn't really necessary as I can still wear a bra under this without it showing, and adds bulk at the front which if removed may help with the closing situation. 

I don't really want to mess around with the zip and there is very little seam allowance there so I'm avoiding that area. The other option is to see if I can drop the shoulders a little. I'm very long in the chest and it is quite tight around the armholes so shifting it all down even a little might result in placing the zip at a narrower part of my back which when combined with the other alterations might make a difference.  

However, I've never done this type of thing before, I don't know what order to try things in and I don't want to ruin the dress. It is snug but it fits well everywhere else and is so goddamn dreamy I'm desperate to wear it.  

So this is where I could really do with some expert advice from my fellow sewers and the refashioners and vintage lovers out there. How would you go about fixing the zip(per) so it meets? What tricks do you have that can magically make extra fabric appear from seemingly nowhere? I'd love to know so I can get wearing this beauty.  And how do you feel about bargain shopping?

See you soon x