You realize physical damage(which is all that Sing can do) won't stop Emperor Han, right? He's immortal unless you stab his heart with his cursed dagger.
You said he doesn't have access to his Palm. And even if he did, Han will simply regenerate and get back into the fight. He has a specific way of being hurt and aside from that he's an unkillable, shape shifting elemental ninja wizard.
But I meant that was before Sing has access to his Palm and once he does (as he seems to have some kind of reactive power level), he might probably send the Dragon Emperor into the sky & likely somewhere faraway and deserted (which is likely B.F.R) if not kill him.
Okay so Buddha palm may not blast people into the air and Sing's durability mostly consist of knife stabs, recovering from venomous snake bites, getting stabbed and smashed through walls and the ground but if that's still not enough he can not only kick large stone debris with expert precision while he's hanging from a wire, but he can curve their trajectories somehow & he even grappled with Beast who's capable of catching a bullet at close range so i guess he might be able to dodge the infinite elements.