I am not sure you have 4000 grafts to spare from your donor. While these boards often highlight large sessions, many people simply do not have that many grafts to spare. Also, the hair in your donor looks fine in caliber, which will also limit what you can harvest and cover on top.
If you had either an FUE or an FUT of that many grafts you may deplete or over-deplete your remaining hair. For someone in your situation, with essentially NW6 status, you might want to consider going in smaller steps i.e. have a 1500-2000 FUE or FUT to restore your front and top and see how it goes.
I think it would be a mistake, IMHO, to try and do a giant surgery all at once given your overall situation.