can you replace lamb with beef and tomatoe with marinara sauce?

Yes, it will still work, but it will not taste quite the same.

Sub beef for lamb at 1:1 ratio,.

To use prepared marinara instead of tomato paste, I'd use 2.5 cups of the marinara and omit the tomato paste and water. After you get that far, taste it to see if it is too thin. If it is, cook it down until some liquid evaporates and the flavors become more concentrated.