Modifying a water tank - Epoxy or PVC cement?

[Glock Diver]

So, I'm knee deep into my fresh water washdown install, and I notice a problem with my tank.  I didn't think it would be an issue before, but now I'm into it.  The issue:  all 3 ports are on a single side, and although the fill hole is at the top, I won't ever be able to get the tank completely full, because the side of the tank with the holes will face aft, and be at a slight incline.

So I'm going to modify this baby, and add a Fill hole to the top of the tank, but I'm wondering if anyone has tried this before.  I'm not sure how they make these tanks (or what adhesive they use), but I'm thinking 2-part epoxy or PVC cement will be the way to go, when I add a fitting to the top of the tank.  Whaddya think??  

[Circle Hooked]

Marine Tex should do the job.

[flounderpounder225]

If that is one of those blown molded poly tanks, there is not a bunch of adhesives that will bond to that material?  Is the tank all one piece or are the fittings on it attached somehow?

[fitz73222]

If I understand what you want to do and you want to plug the existing holes and add the fill hole on top why not just buy some plastic thru hull or bilge discharge fittings and plug them off to seal the old holes. I guess I`m trying to figure out what you need the epoxy for?

[pete]

maybe use an elbow on the fill,pointed up?