Help with ARV on potential triplex

[Levi Dullum]

Hello all, first time poster. I am currently examining multiple properties as a newbie and first time investor. I'm specifically interested in the BRRRR method as I have some capital but not enough to purchase and rehab a property on my own. I have private money to help assist with where I come up short. I've been practicing running numbers on tons of properties and recently came upon an interesting listing. It's an old (1924) 3500 sqft house, 8 bedroom and 3 bath. It appears that at one point it was a triplex but the most recent owners used it as a single home. Asking price is $64,950. I would be interested in reconverting it to a triplex. My issue lies in calculating ARV. It's a fairly rural area with no similar comps. Any help/tips/tricks from more experienced investors on what to do in this scenario? I understand calculating single family homes, but I'd hate to pass up on a deal due to my own ignorance.