Add bath and finish basement?

[Michael Donatucci]

Purchased a 1200 SF 3 bed 1 bath home with unfinished basement in need of rehab that I plan to hold onto. There are a lot of 3 bed 2 bath comps in the area with same square footage that are trading for around 270K that have finished basements. Given I plan to rent, I don't think it makes sense to add a bath and finish the basement. How much is reasonable expectation for downward adjustment for value based on 1 less bed and non finished basement?