Do you have any other bikes you like your fit on to compare?

I matched as close as I could the measurements of my Raleigh I'd been riding for five years when I recently got a '91 Paramount frameset and built it out.

I too got a quill adapter and use a threadless stem instead of the traditional "7" stem. A 17/107 degree stem gave me the flat horizontal stem look of the old "7" styles. If that appeals to you, then consider the headtube angle of your bike when looking at all the different angles they come in. Some only list one angle, but most can be put on upside down.

As for the handlebar height to seat height, It wasn't a big issue as the frame geometry of didn't need a long quill adapter.

The biggest for me was reach. So I just measured from where I sat on my old bike to where I rode on the bars comfortably. Then I looked at what that would be on the new bike and came up with a measurement for what stem length I needed.

Since on my previous bike I had friction shifting on the down tube and safety brake levers, my normal position was on the tops of the bars. knowing my build was going to require me to ride on the hoods or forward drop position to shift and brake, I took the reach of the handlebars into consideration of the stem length too.

If you don't have another bike to compare, then did you like your position of the bike with it's original stem? You can work out stem length from that too.

My Raleigh has a 100mm stem. All my calcs where showing I'd need something in the 70 to 80 mm length for the handlebars I was originally going to get. But a couple handlebar switches with different reaches my stem calc got out of wack and I wound up with a 100mm stem handlebars that my calcs said should require and 80 mm stem.

At first the 20mm extra reach bothered me, but it was just the oddity. No pains or discomfort. 600 miles later I see no need to change it and I ride on the hoods and forward drops with as much comfort as I do on either bike riding on the bar.