You will save yourself a lot of trouble down the road by replacing the shaft even if slightly bent and you would not know if it is (most likely it is). While you are at it, get a pss dripless seal as well. The whole procedure is not that difficult. I have done it twice:
Order shaft, strut and seal, prepare to haulout.
Mark the position of the engine and the bolts.
Haul out, remove the old strut, install the new strut losely.
Lift the engine and remove the shaft from below the engine.
Install the dripless seal, the new shaft, sliding below the engine, through the strut.
Connect shaft to the engine, leaving the engine bolts loose.
Add washers to the strut bolts to align the shaft in the center of the seal, tighten the bolts just a bit.
Run the engine at low rpm's for a couple of minutes. It will position itself nicely, check alignment again.
Tighten strut bolts and seal everything well, complete the pss seal.
Get the boat back in the water, you should have very little vibration, you can safely go back to the dock.
Wait for a couple of days for the hull to settle and finish the engine alignment, check that you have no vibration at high rpms.
You need half a day in the boat yard if you are organized. The trick is to let the engine align itself instead of the endless checking of clearances and tightening of bolts.
Good luck.
SV Pizzazz (H31)