I dont see timing marks on your complete engine? I'm pretty sure the old vs new water pumps will have different depths so that complicates things.
Its trial and error so go for it.
The 67 and 68 SB engines used the bolt on timing tab... With the water pump off, they aren't there...
In 69 they added the timing marks to the timing chain cover housing and eliminated the bolt on timing tab.... But they are still in the same position as the timing tab...
