Road Cycling“It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway
That depends on how the bike is set up. I used to run 4 inches of saddle to bar drop on my old quill stem bikes. Now I can't tolerate that and run less than 2 inches on my more modern threadless stem bikes. I get your point that deep drop bars can allow a higher bar-top position, but I just felt like arguing a little. I would encourage anyone seeking knowledge on aero positioning to heed your words, obviously.
You bring up something here - if the old steel bike is a threaded/quill stem bike, then there's probably room to raise/lower the bars a couple of inches. If the default position is higher, the OP could lower them half an inch at a time and see where his sweet spot is, both with and without aero bars. And all he would need is (probably) a 5mm allen key.