I'm not an engineer, but I'd be surprised to find you could fit Searchwater to a C130 quite as easily as you imply, I'd have thought it would involve significant surgery. That'd still leave you looking for an acoustics fit, as ASW is very much in the acoustics baliwick.
Then you probably already needed your C130 as a transport aircraft - which I suspect is why all the talk about C130 covering the SAR duties of the suddenly retired MR2's didn't seem to turn into actual SAR sorties by C130s.... I am aware that C130 might well have done some SAR that I haven't heard about, but that SAR job in SWAPPS the other week required a French aircraft to go on task as I recall....