It may be just as well. I replaced my rudder alone and wish i had just replaced the rudder box along with it. I think my hole is a little out of round causing hard steering under power.
Don't sweat the added work of replacing the box. Its just 4 bolts and some 5200. You will need to flag down a tool truck and buy a socket that has a big flathead screwdriver end on it to be able to loosen the bolts.
DKJ
1992 Supra Mariah - Red
PCM 351HO 285hp - PCM 1.23:1 Transmission
OJ XMP 4 Blade CNC 13x15.5RH
"People do weird things to boats" -Unknown