Hi There!
I ran your oils through SoapCalc, an online
soap calculator:
http://www.soapcalc.com/calc/soapcalc.asp
I've never used Macadamia Nut Oil before, but it doesn't look too far different from Olive Oil in terms of their fatty acid profiles. Based on that fact, and also based on how I like to formulate most of my soaps with Olive Oil, I came up with this:
Macadamia Nut (50%)....... 650 grams
Coconut Oil (30%).............390 grams
Castor Oil (10%)................130 grams
Safflower Oil (10)................130 grams
Water (full water amount, no discounts)...... 494 grams
Lye (at 5% superfat)..................................186.5 grams
Regarding the glycerin--- I didn't calculate it in because you don't need to soap with glycerin. Glycerin, you see, is actually a naturally occurring byproduct of the soapmaking process itself. There's roughly, on average, 10% (sometimes more, sometimes less) of naturally occuring glycerin in every batch of handmade 'from scratch' soap which is created during the saponification process.
Will this be your first batch? If so, this soap will probably be soft at first, but it will harden up nicely during cure. Let it sit in the mold for about 48 hours before cutting, and then set it on a rack to cure for at least 4 weeks.
I make a lot of Olive Oil soaps and have learned how to formulate using a lesser water amount in order so that my soaps are not soft coming out of the mold at 12 hours after pour, but if you are a beginner, I would stick with the full water amount at first until you get the hang of things. Lesser water amounts can be tricky and move very fast, so it's good to be prepared by having a bit of soaping experience under your belt first.
Hopefully others will chime in and give their recommendations, too.
Always remember lye safety!
IrishLass