Need cash to fund loan downpayment

An SBA loan requires to fund the downpayment with 10-15% of the loan. We are talking about $500k to $750k which I have, but it is invested. Right now, NW: $1.5M (not accounting primary residence): - Rental property $150k equity (rental income is positive) - 401k $550k - brokerage account $800k If I sell from brokerage I am going to be blown next year with taxes although they are long term capital gains. My thought here is to try and maximize the loan (lending) from 401k program (which I won’t be