The approach with the budget is appropriate, when you have a fixed price project, because the planned budget does not change with the progress or the actual work. So if you planned 10 days of work for a task, but you complete it with 5 days of work, you still have the same budget and your margin will rise.
If you are working on a time and material basis, you could define the standard rate of each person as external rate (revenue) and the 'Actual Standard Rate' as internal rate (costs). The standard rate affects the planned costs and the actual standard rate gives the expected or actual costs. Then the amounts of the revenue and costs will correlate to the actual work. The planned costs will show your revenue. And moreover, you can derive your actual margin from reciprocal value of the 'Cost Performance Index'. But you need to adjust the amount of planned hours (or days) to the actual work after completion of the task, so this might not be an easy path either.