If you get stuck trying to find the correct bulkeads give me a shout. I should have some laying around in the basement. If not I can get you a part number of what you need.
As for the Dorso try building them yourself. They are a piece of cake to make and much much cheaper. Lowes will have everything you need.
BTW, if you use a slip fit bulkhead DON'T glue any part of it. You normally don't need/want to glue any of the overflow parts together as they should fit plenty tight without glue. Remember there isn't any pressure running through the overflow.
If you don't glue it together then you can easily clean the pieces a couple of times a year.
Carlo
As for the Dorso try building them yourself. They are a piece of cake to make and much much cheaper. Lowes will have everything you need.
BTW, if you use a slip fit bulkhead DON'T glue any part of it. You normally don't need/want to glue any of the overflow parts together as they should fit plenty tight without glue. Remember there isn't any pressure running through the overflow.
If you don't glue it together then you can easily clean the pieces a couple of times a year.
Carlo