If the money at the brokerage firm is not inside an IRA account, I would definitely REVERSE your percentages! I would have at least $200,000 in cash — given your age and circumstances — and only about $50,000 in the stock market!
The “cash” I would put into U.S. Treasury bills — Read this article. You’ve done a good job of saving so far, and I think you would want to keep the larger amount completely safe. I know that’s very conservative — but if you were my family, that’s exactly what I would have you do. Now.