Dave Tesch believed that 50/50 weight distribution was ideal. Tesch, IMHO, was a visionary because he really thought out the issues of bike handling and conformed them to theories of fit.
Anything from 50/50 to 55/45 rear/front is considered within the range of excellent.
These things vary a little with hand position on the bars (e.g. on the hoods, in the drops, on top) and with all that moving around/shifting back-and-forth in the saddle that we all do depending on terrain and speed.
There does not seem to be an ideal exact measuring position, so the figures are all ballpark.
Don't sweat if your measured values go a percent or two in either direction. Those are well within the margin of error provided for by the postioning variables.
So anything from 50/50 to 57/43 rear to front in you livingroom should be just fine.
You know too much weight is on the rear when you are able to pull a wheelie while hill climbing.
You can check with just one scale under one wheel as long as you keep the other wheel elevated exactly as high as the scale (use kitchen cutting boards, large books or magazines to fit) and then just subtract the scale wheel weight from the total weight of you standing on the scale with the bike in your hands.
My experience is that a proeperly fit custom made frame will fall within the desired range.
Emanuel Lowi
Montreal, Quebec