TripAdvisor has a dozen entries under "Nature & Parks in Manado" some of which include a map and/or an address.
I doubt they are all quite what you are looking for but wonder whether just one Tangkoko Research Station might be sufficient. On the northern tip of Sulawesi, so about two hours northeast of Manado rather than about four hours southwest. Wikitravel mentions:
... a variety of hardwood trees and unusual plant life. The animal life is also quite varied, and one can often view Tarsius tarsier(world's smallest primate), black tailless monkeys, Maleo Birds, wild pigs and kuskus (marsupial family)
Flora and fauna
Tangkoko Nature Reserve protects at least 127 mammal, 233 bird and 104
reptile and amphibian species. Of these 79 mammal, 103 bird and 29
reptile and amphibian species are endemic to the island.
Threatened mammals include the Celebes crested macaque, of which about
5,500 remain on the island, the Sulawesi bear cuscus and Sulawesi
Babyrousa celebensis image courtesy Masteraah at German Wikipedia
For mammals they mention: Crested Black Macaque (Macaca nigra), Spectral Tarsier (Tarsius spectrum), Bear Cuscus (Ailurops ursinus), Sulawesi Dwarf Cuscus (Strigocuscus celebensis), Bats (the commonest Rousette (Rousettus celebensis) and Lesser Dog-faced Fruit Bat (Cynopterus brachyotis) but the island is home to 20 other species, including many rare and peculiar forms about which little is known Tangkoko), Northern Dwarf Squirrel (Prosciurillus murinus) and Pale Dwarf Squirrel (Prosciurillus leucomus), Sulawesi Forest Pig (Sus celebensis), Babirusa (Babyrousa babyrussa), and Timor Deer (Cervus timorensis).