2 P classes, some H sets and R707 are heading down to Stony Point (Although R707 is only running between Melbourne and Frankston). There will also be a single car sprinter, which isn't rare, but could still be a good opportunity to see
Taits are running between Eaglemont and Clifton Hill
Stony Point timetable:
Southern Cross: 10:16
Flinders Street: 10:30
Caulfield: 10:50
Moorabbin (arr): 11:10
Moorabbin (dep): 11:21
Frankston (arr): 12:08
Frankston (dep): 12:38
Somerville: 12:52
Bittern: 13:07
Crib Point: 13:12
Stony Point: 13:15
Return
Stony Point: 16:35
Bittern: 16:44
Hastings: 16:48
Somerville: 16:58
Frankston (arr): 17:10
Frankston (dep): 17:23
Carrum: 17:33
Mordialloc: 17:44
Moorabbin: 17:55
Caulfield: 18:03
Flinders Street: 18:17
Southern Cross: 18:34
The taits don't have a very good published timetable, but the transfer leaves Flinders Street at 9:51, with the return transfer leaving Eaglemont at 15:00 arriving at Flinders by 15:30. There's also shuttles between Eaglemont and Clifton Hill leaving Eaglemont at 10:20, 11, 11:40, 12:20. 13:00, 13:40, and 14:20
So get out and go get some train photos! It's entirely possible to see both