4-plex with fire damage: a great place to burn money?

[Christine Kwasny]

I am currently negotiating a purchase of a victorian 4-plex.

The pros:
Amazing location in one of Portland's hottest neighborhoods.
Immediate upside potential-rents could handle a 20% increas w no improvements; 30% or more with minor upgrades with additional anticipated increases as neighborhoods continues to gentrify.
Very cool building that has many updates already (electrical, plumbing, windows).

The cons:
Roof needs immediate replacement. Not leaking but roofer won't certify. $20k
Attic shows signs of historic fire damage with charred framing. $35k to rebuild and permit.
Date, cause, and extent of fire damage is unknown. Damage could extend into ceillings and walls and require replacement. This would also make top two units uninhabitable during repairs. Repairs: $70k+++?????

Seller will not do any repairs. What to do?

Walk away? Is this a pandora's box of potential grief?

Replace the roof, make minor improvements, enjoy cash flow, and deal with fire damage upon sale or much later date?

Fix it all now with permits and hope costs and timelines are within anticipated estimates? Like how often does that happen?

Any insights are appreciated!