ryo and bu and shu...oh my! (stuck on Japanese weight units)

[Ōgiyame no Emi]

I recently came across some recipes for classic neriko, which was very exciting. As was the discovery that two of those blends, the summer Lotus leaf (kayô) and autumn Chamberlain (Jijû) require no musk... meaning that I could afford the ingredients and actually have a go blending some kneaded incense.  I have a friend who will be moving into her first flat and has never been allowed to burn incense at home; I thought some handmade neriko would make a lovely moving in gift.

While there is a degree of flexibility with the recipes' ingredients and their amounts (Chamberlain and Lotus leaf give lily petals as a replacement for musk, however Blackness and Plum blossom do not) I'm coming unstuck on the units of weight themselves. My searches come up with contradictory results even before attempting to translate archaic Japanese units into ounces and then into grams. I'm beginning to doubt my notes, and would rather re-do some calculations than wind up buying the wrong amount of powdered aloeswood or other ingredients.

Can anyone help me with an accurate oz/g conversion of ryo, bu and shu? Below is what I've found so far on them (please all feel free to point and yell if incorrect, as this is just what I've gleaned from google):

1 ryo = 4 bu = 16 shu? 24 shu? 

1 Ryo/Koban):    15 grams     = 4 Bu
1 Bu:                0.4 grams    = 4 Shu
1 Shu:              0.07 grams

[solveig]

Noble Cousin!

Greetings from Solveig! According to 『国語国文学手帳』Shogakukan, 1990/1993 p. 245.

1 貫 kan        6.25 斤 kin (approx 3.75 kg)
1 斤 kin        16 両 ryō (600 g)
1 両 ryō        10 匁 monme (37.5 g)
1 匁 monme 1 匁 monme (approx 4 g)
1 分 bu         1/10 匁 monme
1 厘 rin         1/10 分 bu
1 毛 mō         1/10 厘 rin

Do you have the kanji for the units in question?
Are you sure that all of your metrics are weights? Perhaps some of them are volumes.
That said, it sounds like you are looking at monetary units: 4000 mon = 16 shu = 4 bu = 1 ryo.
Monetary units fluctuated rather a lot. That said Wikipedia has the following to say:

The Koban (小判) was a regular ovoid gold coin, equivalent to one Ryō. The initial Keichō Koban (minted from 1601) had a weight of 18.20g. The 1714 Sado Koban (佐渡小判金, 4th year of Shōtoku) also had a weight of 18.20g and was made with an alloy of typically 85.69% of gold and 14.25% of silver.[4]