This is what you need for the S52 swap.
E34 525i oil pan 1113 174 0346
Oil sump gasket 1141 170 3947
Oil sump (suction tube) 1141 174 8150
Dipstick tube 1143 173 8169
Dipstick 1143 172 0875
Dipstick o-ring 1143 128 7541
Also there's a ton of information on R3VLimited.com. You just have to sift through it all to get what you need. As well maybe contact some of the guys that are or have done the S52. You might want to keep it OBD II or convert back to OBD I. If you have any other questions I might be able to help because I'm doing the same swap, it's just taking me a while.