Hello. My mechanic diagnosed that I need to have my lynx's head cylinder gasket replaced because the engine is draining water from the lynx's reserve tank every now and then. The mechanic also advised that there might be a need to machine shop the cylinder block. Is it better to have it serviced at the casa or just some credible autoshops around? Will it have any effect or bearing on the engine if the job done was not good? Please help again. Thanks.

OT: The lynx recently had an overheat and this was (as the mechanic said) one of the cause of the problem. TIA ...