You need KYC (as required by Bangko Sentral ng Pilipinas). But in my experience, KYCed na ang GCash ko when I registered using my postpaid number.
Kung walang KYC sa Maasin, try mo sa Tacloban.
I'm from Maasin City, Southern Leyte. They do accept GCASH KYC since I had mine KYCed there a few years back. Just cash-in (to self) your GCASH account and they'll tell you that your account is not yet KYCed and they'll gladly do the process for you. Hope this helps. The cashier there is very accommodating.