Jeezus Christo guy, I’m not a doctor or a fortune teller - just a bro on the internet
I can’t tell you how much AI you “need” because people guys aromatize differently. But the aromatization from HCG is largely in the testes, and the AI can’t prevent that, so you can only really limit total estrogen by preventing the already circulating test from aromatizing. HCG also effects guys estrogen differently, but you can bet the larger you decide to dose the more it will raise estrogen for you.
You do ideally want to be closer to bottomed out than healthy/balanced, so I would PERSONALLY at least maintain your current AI dose or increase it, depending on how you seem to respond to HCG (pay attention to your water retention or if your erections become limp).
For me, if I take even 250iu of HCG I need an extra weekly dose of 12.5mg exemestane. On 400 test and 500iu HCG per week I took 3 doses of 12.5mg exem. I have high bodyfat and aromatize pretty significantly.