@Kevin G. I have purchased a fire damaged property to hold. I agree with @Eliott Elias if after you have done all of your due diligence (see below + all other rehab costs) and the numbers still work, go for it.
I completely agree with @Chris Seveney on making sure an engineer looks at the boards to make sure they are still structurally sound. Your engineer should be able to offer you an engineering report stating it is structurally sound with their stamp (if it is). This really helps a potential buyer.
@Andy Sabisch Yes, encapsulating the wood is a great way to go, we did the same thing.
@Chris Merchant I also agree on making sure there was not additional water damage from the FD putting out the fire.
@Carlton B. has a good point as well for the electrical. When we purchased the property we had to complete a state electrical safety inspection to make sure all electrical was 100% repaired on all fire damaged items. Oil based Kilz is a life saver!
Kevin, can I ask what kind of hard money rate, points, fees and term you are able to get on this type of project in the Bay Area today?
Best of luck with the project!