I don't often brew oolongs western style. For most of my brewing, with multiple steeping in mind, the water temperature depends on the tea. I often start oolongs at 195 degrees for 1-3 infusions. I do that especially if I am packing a lot of leaf into the pot in anticipation of many sessions--with some of the darker oolongs especially, it's hard to make those first infusions short enough to avoid some bitterness, so starting with slightly cooler water can make the first infusions smoother.
And how many steepings depends on: how much leaf I use (more leaf/more infusions); intrinsic characteristics of the tea (Jin Guan Yin seems to give fewer infusions than the best Ti Guan Yins do); and external factors like whether it's close to bedtime and a series of very dilute 'sweetwater' infusions sound just right, or I'm seeking a bit more buzz and want to start another set of infusions. Put all that together, and the total steepings for a single set of leaves might vary from 3 to 12 or more.
Back to the 'western style' question: sometimes, if I know I have the capacity for just one round of tea, I'll brew with much less leaf (since I'm going to do only one infusion), for a longer time. Since I don't do it very often, and because I'm a bitter-wimp and I drink my tea more dilute than most, I don't have a set grams/mL ratio that I can suggest for you.