Clive,
The 660 bronze will work fine for your pump body and for any low/medium speed bushings you may need to make in future with the leftovers. I'd use it before using brass. Some brass I've bought lately is really low quality. One rectangular bar actually split down the middle lengthways when I tried to drill it. The broken edges whoed a "cold shut" type defect where it had been forced together from two pieces. Garbage.
I've specified many machine parts professionally over many years in 660 bronze in industry and never had a problem with it. These include bushings, structural elements with a bearing function, and custom valves and pump parts. Generally 660 bronze is not considered a weldable or solder grade material, although it probably could be, in a pinch.
PhBr would be better for soldered boiler fittings. You can order PhBr from McMaster Carr or Small Parts Inc. in USA. It is expensive. Metal Supermarket can get PhBr by special order but in my local one it is difficult to get staff to pay attention long enough to order it and then call when it is in (and not sell it to someone else before you get there).
I'm in Waterloo Ontario, where in Canada are you? Private message me if you'd rather not put location details in the forum. (My German shepherd , alarm company, and shotgun are not too concerned) JD