Hi Kusala, I wonder if you have looked at the Buddhava.msa which has heights and other data for the past 25 buddhas. I wrote about it in my blog: http://kalyaano.blogspot.com/2010/12/bu ... uddha.html
I am also not sure about length measurements in Paali. There appear to be some inconsistencies among commentaries. I don't understand why there are two different units of measurement for stating the heights of buddhas in the Buddhava.msa. I worked back and forth with the attempt to make a comparison. If the relatively old English translation of the Buddhava.msa is right (I have my doubts) and my calculations are accurate, then the heights of buddhas have varied from 10m down to 1.4m. This is based on the assumption that Gotama Buddha was 2m tall. All this highly speculative and marginal to Dhamma practice. Even so, it is inspiring and can increase confidence for some people.
May you be happy, well and peaceful.