Save the time and just buy a set of refillables. I have them for all my K3 Epson's except the P800. 9900, 9890 and 3880.
I advertise and purchase any K3 ink I can find. Paying .05 per ml (Sometimes more)
I have stopped purchasing as I now have over 10,000 ml of OEM K3 ink. There is a lot of K3 ink out there.
All you need is a syringe and you can pull the inks from any OEM cart you purchase and reinsert it in your refillables.
You just cannot reinsert ink into OEM carts. (Unless you do the port retrofit for 3800/3880 carts)
Shades of Paper in New Jersey is running an ad for expired OEM K3 inks this week.