By receptor, do you mean the floor, typically called the pan in a shower? All pre-made pans that I've seen (now that isn't all that many!), are symetrical and have the drain in the middle. If you can't move the drain, then you'll have to have a pan made. www.schluter.com makes a pan that then has a waterproofing membrane attached that is made out of a high density foam that is made to be tiled over. You can check the sizes of those, but I'm not sure if there is one that would fit. They can be cut some, if the stock size is not what you want. If you don't want tile on the floor, then you are probably out of luck for a preformed one, if you must have things (the drain, and dimensions) as you indicated. If you were to have a mortar pan made by a qualified mason/tile-setter, then it is eminantely possible. A partner site is www.johnbridge.com for tiling info. First, though, I'd consider determining if moving the drain to the middle of the floor is reasonable. It could be easy, then you'd have more choices.