One of the deciding factors was the tacho needle that kept moving between 1100 & 1350 rpm on engine warmed up idle. Cracks confirmed by spraying WD 40 around inlets that increased idle speed.
Ask yourself if you intend to keep/ride the bike long term-also it will be impossible to synchronise carbs for best performance if you have air leaks.
While carbs were removed I took opportunity to overhaul same with kits(also from M&P) & generally check condition of fuel hoses, carb heater hoses & clips, wiring & plumbing of bike generally-its an investment in trouble free riding. Of course my OCD doesnt help!