That seams a litle steep. I have sent several pairs back to mercury and once given the estimate the end price wasnt much higer. The first rebuild to the original owner is discounted to 18,000 per which includes a ton of parts
bearings, rod bolts,gaskets,lifters,springs,valve locks, retainers,valve seats, rocker arms rebuilt, rebuilt blowers , all new sensors, belts ,hoses all the block and head work , pistons, rings ,seapumps .If upon tear down if any aluminum part is found deteriorating it will be replaced at add $ . Every pkg that I have returned looked like brand new and came with bokes of all the old replaced parts. Still your price sounds very high.