I'm built like you, maybe even more out of proportion. I can flat foot 63cm frames and I am only 6'1".

I have tired it both ways and now seem to be back with the tall frames so that the bars are naturally high. I have some lower back issues. I need the bars high for long rides or I might have to be carried off till I can straighten up.

With the tall frame I find myself on the nose of the saddle when climbing (and we do a lot of that in north GA) and tried a few things so far.

I tried going with a 40cm bar that came on my 58cm bike to cause the elbows to come in thinking my reach would have a tendency to stretch but found it was hunching my back between my shoulders in an uncomfortable way that gives me neck complaints. Just swapped to a 46cm bar and like the stability a lot more and already seem to have less neck fatigue. I ordered a Ergo bar that had short tops to shorten the reach when on the hoods. Plan to get a long ride in today and see how that does with the shoulder and neck pain.. So far it is better and I think the shorter bar offset the extra reach of the wider bar.

Interestingly the 44cm bar that came with (but was not installed) the 63cm frame made the 58cm frame seem better as well. That leads me to believe that matching the bar width to your shoulder width is a lot more important that I ever thought.

I think I am still going to be up on the nose some but the wider bars flattened my back out increasing my reach more then the narrow bars did. I have a 80mm stem I am about to order for a bike I am building for my 5' wife. That will be my next thing I try.

You might talk with your LBS fitter and see if you can work out trying a couple of different stems one morning and make a couple of mile loop before dropping the coin on one.