1&1/2" close coupling kit Euroflo Cistern Coupling Kit | Toilet Accessories | Screwfix.com, and a Dudley Turboflush adjustable siphon, Thomas Dudley Ltd Adjustable Siphon 237mm | Fill & Flush Valves | Screwfix.com (alter height to suit your cistern, has internal overflow), and you should never need to worry again unless replacing the entire toilet.
Got these in both my WC's, makes it easy to change the washer when need arises and otherwise shouldn't need to touch them. Far superior flush to any modern pan.
Got these in both my WC's, makes it easy to change the washer when need arises and otherwise shouldn't need to touch them. Far superior flush to any modern pan.