I agree with Mick....you'll need to learn a whole lot more about the engines
before you take the grinder to it, that's for sure. Another thing to watch out
for....if the liner is ABC....with a chrome bore....and you grind through the
chrome....you run the risk of peeling the liner and such, because the chrome
is applied after all the machining is done on the cylinder. Once you grind the
chrome off the champher, bad things can happen.

On the other hand, if the engine is ringed with a steel liner you can grind away
on it till your hearts content, but you must re-champher the ports.

Generally speaking, you don't want to mess with the transfer ports and mess
with the direction of flow. That has been carefully worked out ay the factory
and you won't improve on that.

FBD.