G'da Worty.
Another + for the premium concentrics is the pilot jet is accessible from the outside (don't have to drop the bowl on early ones, non changeable on later ones) and a "stay up float" with a metal adjustable tang, and made from proper aluminium.
I use 98 in both mine. As Burger said she will soon let you know. Higher octane fuel needs the timing one to one/half degrees advanced as it burns slower but with more punch.
Cheers