Need Advise From Builders

To be more specific, is more of needing advice with an old project of mine that I've put off for a while and need to finish. There is this puzzle that I could not solve, and it has been my limit of rebuilding. Here is the puzzle I am stuck with:



Now, I just can't improv the missing area because it won't be exactly like the original. With excellent building skills do you think you know how to complete this by just using the image? If there is anybody who can help me out, I would really appreciate it!



Here is the only clear reference I have recreated from: