Scotland has no deficit at the moment. What share of the current UK deficit Scotland might accept on gaining independence is a matter for negotiation.
Every country on earth has a deficit except one. Norway. (Actually that's what they say but I wonder about Dubai and Kuwait and some other places like that, but leave it for now.) What country does Scotland most resemble in terms of natural resources, except Scotland is better off? Why Norway actually. If Scotland, like Norway, had been independent in the 1970s when oil revenues started to flow we may have handled these as wisely as Norway did or we might not. Nobody knows, because we weren't.
I've heard unionists (even Scottish ones) crowing "England took all the oil and pissed it away and it's gone now and Scotland's bankrupt so can never be independent and England owns it forever, yay!" and that's only slightly paraphrased. Declaring that a country's assets were squandered by another country who had control of them at the time, therefore the country that owned the assets must let the squandering country manage its affairs in perpetuity seems irrational to me.
Ireland took none of the UK defecit when it gained independence, as part of a negotiated deal. Sturgeon is prepared for an independent Scotland to take some of the UK deficit, and she has made that quite clear. How much, who knows?
Any assessment of Scotland's finances at present as they might relate to EMU criteria is purely notional. Scotland doesn't have control over its own resources or spending. It turns 100% of its resources over to Westminster and gets pocket-money back. Westminster largely decides what gets counted as Scottish revenue and Scottish spending and (here's a shock) it has consistently understated the former and overstated the latter since it started doing the sums.
GERS was originally dreamed up by a Tory government explicitly as a way to keep Scotland in the union by making its finances look bad and making it appear dependent on "handouts". After Swinney got some control over what was and wasn't counted it got better, but it still excludes swathes of stuff - exports of Scottish products that leave the UK from English ports or airports for a start, most whisky revenue, a lot of revenue from UK-wide companies with HQs in England for example. It also includes things that no sane Scottish government would ever spend money on, from a chunk of defence spending (think Trident, and invasions of countries like Iraq), and even a per capita share of spending on things like the London sewers and the Olympics. In contrast the Forth Bridge and the Commonwealth Games and the upcoming dualling of the A9 have had to be entirely financed from Scotland's pocket money.
Look at it this way. You're a girl of marriageable age. I nice young lad is courting you. He owns a farm. The farm's finances look pretty disastrous on paper. If you take him on, will you be in penury all your married life? But you look at the farm. It's quite large and fertile and the climate is excellent. It has mineral deposits and renwable energy potential. But it is currently being run by your nice lad's neighbour who takes all the decisions about what to plant and what to rear and how to manage everything. There's also a suspicion that some of your lad's farm's revenues might be finding themselves on the credit side of the neighbour's books, and some of the neighbour's expenses on the debit side of your lad's farm's books.
But if your lad marries you, he gains personal control of his farm. He can run it as he best sees fit. He might find himself with a bit of debt at the beginning, remember those accounting anomalies and the atrocious way the farm has been run, but he seems a hard worker and he has a good degree in agriculture. So, are you going to look at the books and say, no way, I'll find myself an investment banker instead? Or are you going to look at the blatantly obvious potential of the farm itself? Another neighbouring farm with excellent resources (but still inferior to your lad's farm) has been well run by its owner for the past 40 years and that owner is now so filthy rich he and his descendants are set up in perpetuity.
Are you going to marry him and set about making that farm as prosperous as the other farm's example shows it can be? Or are you going to turn him down on the basis of these current accounts which he didn't create and couldn't influence?
Every time-point where I have been able to find some commentary, from 1720 (Daniel Defoe) to the 1960s before oil (John Jappy) with several in between has shown Scotland to be losing out overall from the union. Having capital and resources bled away to London, starving the country of infrastructure and investment. After oil, and Thatcher, it only got worse. I'm in favour of stopping that particular type of self-harm.