How to Comp a quadplex in San Diego?

[Mike Hsiao]

I've been looking at a quadplex in San Diego area for sale that I'll call Property A.  Property A is built in 1940, 2400 sqft building on a 6700 sqft lot, 4 car garage There are no interior pictures, but if the inside follows the outside of the properties, I'm guessing it hasn't been maintained or remodeled recently.   

I went on Redfin to find multi-family properties in the same zip code that sold in the last 3 months. The closest i found  was a 7 unit (Property B), built in 1985, 5693 sqft building on 7,000 sqft lot, 7 car garage just 2 blocks up from property A.  It sold for $574/sqft.  

I asked my agent what he thought we should offer on Property A, so he tried to pull up only quadplexes that sold in the last 6 months. He found one that sold back in June 2022,  was a couple miles away in a nicer neighborhood.  I told him that wasn't a good comp because the neighborhood is quite a bit nicer.

He said my comp wasn't accurate because it was a 7-unit.  Yet he also sent me a triplex as another comp, but still a couple miles away from Property A.  This is in an area where neighborhoods can change pretty quickly street to street.

I know valuing a multi-family property is different than single family, since you need to account for the income and expenses, but my thought process was to take the $574/sqft sell price of property B, and discount it lower to ~$550/sqft given that Property A is much older building and likely would need a lot of rehab. And the street is a tad bit less desirable than property B.

To me, property B was more accurate based on the location.

Thoughts on how to best go about valuing Property A?