Your valve seats are already suitable for unleaded fuel when the bike was made. The metal beads are snakeoil product so throw it away. You could run on unleaded cheap fuel as your compression ratio is lower than a T120. I use Shell super unleaded which is higher octane, or the Tesco Momentum version which is 99 octane. These fuels all have E5 in the UK. I would use the Shell higher grade for the safety against any pinking under load. I have 8.5 compression ratio and i can run the lower grade but i suspect it would knock a bit with a pillion and going uphill. Not worth the risk for just a little more money. The battery should not spill if you get a sealed for life type. Halfords, Yuasa range will last around 4 years. I am using Yuasa fire alarm batteries again now at £16 with a life of 5 years. NP7 type. i see no need for paying £40 for a specific battery. I have used these fire alarm batteries for over 20 years without any problems. They can be fitted on their side if you like, but not upside down. They will not leak at all. Spade terminals are fitted.. If you just want a battery now, buy the Halfords product. You might be able to get a Halfords trade card and get 20% off the battery.