If that was the only problem, it could have been easily sorted with a longer post. The variable you can't do anything about is top tube length.

I'm not sure you're going to get much useful advice with the scant info you've provided; all I can tell you is that 58 sounds like roughly the right size for a 6'1" bloke. However, it depends on the ratio of your torso length to your arm and leg length.

It's not about getting any old bike you can 'adjust' to you by hanging odd-sized bits off it; for example if you fall in the middle of the bell curve for proportions, you should be using a stem close to 120mm. If you have normal proportions and you need to use a 80 or 150mm stem to get comfortable, something's wrong and the bike won't handle right.

I'd suggest researching the question a bit; you should be able to find a spreadsheet you can plug your measurements into in order to give you somewhere to start. Then I'd test ride some bikes to get a feel for what difference small changes make.

Coughing up for a nice bike when you're not totally sure if it'll fit is a bad move. We can't make you totally sure; you have to experience a good fit for yourself.

Just to complicate the picture even further, you may find the perfect position doesn't feel like it at first, and takes some getting used to... on the other hand, there's prolly no such thing, given the number of compromises involved and our ability to get used to almost anything. But just beware of 'different' feeling 'odd' - it usually takes a few minutes at least to adjust to a change in position, so reserve your judgement.