G'day Bonny,
The comp ratio rises quite a bit, put your thinking cap on. If the A7 has 8 to 1 comp that means the combustion chamber is 31.25cc, 250 div by 8 = 31.25. So now the A10, 325 div by 31.25 = 10.4 to 1 comp ratio. That's what I'm running on the cafe. Ping city.
If you use a dremel to blend the outer edge of the comb chamber to match the bores the ratio would drop to around 9 to 1. With te head still on, wind it over to TDC. Lean the bike over so that the spark plug hole is vertical. Now use a syringe and measure the amount of oil it takes to come up to the bottom of the spark plug hole. This will tell you what the cc of the comb chamber is to work out your comp ratio.
You could also use the dremel to open up the manifold to match a 26/28mm carb.
Sounds like a lot of work but it's not really.
Cheers
PS to get the oil out just lean bike back over the other way and use petrol and compressed air. Don't loose the tip off the air nozzle, LOL some will know what I mean.