XTR 987 piston size

I have an XTR 987 caliper that is continually giving me issues with sticky pistons causing brake drag etc. A new brake set isn’t in the budget at the moment. I did find a 985 caliper on EBay for $90 but that’s still more than I want to spend. I’m thinking about trying the replacement pistons and seals from China but they don’t list 987 as compatible. Does anyone know if an XTR 987 caliper piston is the same size as an XT 785\SLX675?