What kit(s) to buy for a mild 904 rebuild?

Honestly I agree with above….
Buy a proper tear down/ rebuild book- eBay like $25
Tear it down and actually see what you need. Some kits are gaskets only. Some have bushings and seals and some come with everything plus a kitchen sink (lol!) If cost is your bug-a-boo like it is with most of us or your nervous about the tear down…. Watch a few videos on U-tube. There are many.
Then tear apart and physically check all parts then that will tell you the level of kit you need. Most 904’s are over 40years old and have been touched by others for one reason or another.

Good luck! You got this.
Syleng1