"Liberal" Co-op Liquidity Requirements

I am about to place a bid on what my broker has termed a "liberal coop" (20% down, unlimited subletting) on the UWS. My housing DTI is 22% and total DTI is 28% (no CC debt, just student loans). Credit score is over 800, I have been employed at the same job for 11 years and have been consistently promoted so I believe all that is solid. However, I have a question about post-closing liquidity requirements: is there a rule of thumb for "liberal coops"? I ask b/c after down payment/closing costs, I will only have about 20 months of "liquid assets", cash/stocks (401K adds almost 250K but I know that doesn't count as liquid). Is that generally sufficient?