you have illustrated the problem of buying online when you have no idea of your ideal size/geometry.
once you know this a quick look at the geometry chart for that model will be all you need.
you could always go to a proper shop and get fitted but then you might end up paying more for the bike but obviously getting more in return.
if you find a shop with that model in the size you think you need then at best you will get a quick sit on it but if it's unbuilt that isn't going to happen. is it really that much of saving when for a bit more you can get fitted properly and probably get the stem swapped to your ideal length too.
you have illustrated the problem of buying online when you have no idea of your ideal size/geometry.
once you know this a quick look at the geometry chart for that model will be all you need.
you could always go to a proper shop and get fitted but then you might end up paying more for the bike but obviously getting more in return.
if you find a shop with that model in the size you think you need then at best you will get a quick sit on it but if it's unbuilt that isn't going to happen. is it really that much of saving when for a bit more you can get fitted properly and probably get the stem swapped to your ideal length too.