Well first of all, we have differing opinions of "strong as hell" because when I think 9% THC I think KB or low grade.
Well... my advice is generally always the same, and I've said it time and time again, but nobody seems to ever want to listen:
*START SMALL*. What I mean by this is start with a mixture of something like this:
400mg 018 / 100mg 073= 500mg JWH.
500mg JWH into 15g of product (I *highly* suggest Damania and Raspberry leaf for many reasons - mostly it will not go stale, it tastes good, burns smooth and slow, and will absorb 100% acetone quickly and efficiently without loosing any product).
That's going to yield a product of ~40mg JWH / 1g. Now this may at first seem high to you, but in reality, it isn't. Your tolerance is going to build fast. It seems rather common that people start at the 2mg-5mg dosages and within a week they're up to 25mg-30mg. Personally, I can smoke 60+mg in a sitting without getting those common "OD" feelings. So this means (to you) that if you make a ounce with a 10mg/ 1 g batch, it's going to be useless to you half way through as it will delivery a shitty high.
So the mixture is up to you - but the best advice I can give you is DO NOT set a high bar. You want to use a little bit for your first time unless you're Mr. Money Bags and don't give a shit about wasting several batches trying to find your sweet spot.
And yes, this thread belongs in synthetic, and I have answered this question countless times. If you want to listen to the advice I've given, great. If not, enjoy experimenting, because that's what I had to do 8)