Swapped out the old pads for the new ones. I went to Supercheap Auto and saw a compound that looked like the rubbery stuff I took off and I had $8.50 credit on my rewards card which was going to expire shortly, so I used it to buy the stuff cheaply.
It was a bit fiddly getting the old ones off as the caliper has to come off to get them out. While I was there I noticed that the cutout on the backing plate was a little snug and the pads were jamming in there.
Took the opportunity to use my grinder and make them fit in the backing plate a little better.
I wondered if I should but I could see that the calipers were actually retaining the pads and holding them from slipping radially so I reckon it's ok.
Used the anti squeal compound as per instructions and got everything back together and done. I'm leaving it till tomorrow before driving, giving the compound a bit of time to harden up. Apparently it doesn't go completely hard and stays a bit tacky.
I'll post again tomorrow after a test drive and give the verdict.