Wow, I had an '82 h27 and....
replaced my cutlass bearing....check the archives, it's quite a comical story...ended up breaking my hand (punching the boat out of frustration)...will never do it again, but........you need to drop the rudder...then, disconnect the shaft assembly and pull the shaft out...then, take a hack saw blade, and cut the old bearing out, then, have the new bearing frozen (yes, frozen...the metal will contract), and, with a C-clamp and a block of wood install the new bearing, but be VERY careful not to rupture the brass (I found out it's very sensitive to pressure)....good luck!!!!!!!!!!!!!!!