Not sure how old is the building and what is the current condition.
1. How old is the roof? It could be $10k to $15k cost if it needs replacement.
2. How old are the 8 HVAC systems? If more than 15-20 years, it could easily cost you $50k for replacement.
3. How old are the kitchen cabinets/ countertop and appliances, and the bathroom condition? Kitchen and bathroom are the place that you need to update before increasing rents.
Hope it helps.