Without knowing I've probably been riding frames "too large" for me. In quotes because I feel comfortable and fast. I've modernized some vintage road bike frames with new components and now bought a very cheap look kg486 from a pawnshop on ebay haha without knowing the size.

I'm 5'10" and it seems to be a 58cm maybe 59cm as far as I can tell. I can stand over flat footed but only with some parts to the side ha. I know a smaller frame is ideal, but if through stem, crank arm length and seat adjustments I can get comfortable...does it even matter? I bought the bike in an attempt to better some hill climb times I've been focusing on on Strava haha.
In the end I'm asking if I'm comfy is it a big deal. Handling may be different or not ideal for uphill sprints but we'll see when I give a few a go.