@David Stroud IM Roadster D I bought some shrink stuff at princess auto but they usually have only the 2 to1 shrink... At Gervais Electronics you can find 3 to 1 and I think 4 to 1. Allied as well might have it off Merivale.
4 to 1 is not cheap. I found a piece on AlieExpress from China, for not much money and I waited a bit to get it... If you only need a bit I can give you some.