I am not getting the focus on headtube and stack height unless you are trying to figure out of your current steerer is long enough for the new frame. Stack height really isnt relevant to fit. I am not familiar with Lynsky geo, but on most frames, HT increases as frame size -- usually measured by ST -- increases. For example, my 58cm Cannondale has 17.5cm HT; a 60cm C'dale has 19cm HT. So I went with the frame that had best TT length for me and took the HT that came with. I agree that a smaller HT with lots of spacers looks kind of odd, however, and based on your proportions, I imagine its kind of hard to find an off the shelf frame that fits well (my height is evenly split between leg and torso so the even proportions of my Cdale -- 58cm ST and 58.5cm TT -- fit me well). With your proportions, it seems to me you need a larger frame vertically speaking with a relatively short horizontal reach, which is not the norm. That would give you less drop without needing a really long steerer and lots of spacers . So if you can make the larger frame work reach wise by going with a relatively short stem with some rise, thats the way I would go. That said, your best bet would be to get a professional to do a bike fit for you. Then you would be better able to dial everything in.