You 'can' get away with replacing the rings only but there's a number of pitfalls in doing so. If the bores are ovalled out or have vertical wear grooves in them the rings will only be a band aid solution (it will also depend on the condition of the pistons as well). You'll get by with a light hone if the bores aren't showing signs of excessive wear (race engines are built with greater bore clearances, but are in by their nature designed to be pulled down and rebuilt every race season) so technically it's a feasible approach...