How do I calculate the numbers with a loan assumption?

[Gabriel Jordan]

Good morning, 

I was looking for some help figuring out what I should offer on this house (would be my first property). Here is the situation. It's a small 3/1 in a d2 college town located about 5 minutes walking from campus. The house was sold in 2021 for 150k to the current buyer (brother's girlfriend). It is 1,008 sqft. The most recent comps are from Oct, the rest are may-sept last year. The comps are between $118-$141/sqft, but it was purchased at $148/sqft.

The loan is assumable at 2.75% rate ($139,383 principal remaining) but will cost $900 application fee and  between 1-5% of purchase price (assuming 2.5%). The estimate is that the house is worth about 160-170k based on comps. It is in good shape but probably needs 2-3k worth of cleanup to make rent ready. Oh and based on research it would rent for about 1.1k on avg

I have used the calculator to try and crunch the numbers but I do not know how to layer in the loan assumption. 

Thank you for your help!