The piston dome sand/grease will wash off after pulling the wrist pin. The issue of painted over pockets of sand in the crankcase is tougher. I poked around carefully in my crankcase with a dental probe, but even after finding and cleaning out the piston sand, and checking the cam covers, I still have a hidden sand source, though now it is minimal. I change oil often and use a gravity fed bypass filter just below the big door.
If I was starting over, I'd strip the crankcase via the lye in plastic trash can method that Quinn described here, then take my needle scaler to the interior before glyptol'ing it on the inside.
I know one guy here recently did a very good cleanout job without disassembly and then found no sand problems on his bearing shells after running for a while. I only wish I'd been that lucky.
I do agree with the others, if you want the best service life, it's best to tear it down completely and check things over as you clean and reassemble. There are no set parts that you'll need, you just have to wait and see what surprises Rajkot provides.