Thanks for that fellas, in the UK fuel isn't really an issue as 97-99ron (different system to stateside) so 10:1 should be fine

Any reason not to stay 86mm? Only as as the Pistons I already have are 86mm so seems daft boring the block to fit different Pistons unless 86.5 has a big advantage?

That all sounds simple enough what you have said and it we actually sort of what I wanted to hear lol.