Lots of good tips already in this thread -- I'll throw in a couple:
That one hard-to-reach header nut (on the driver's side I believe it was) -- you can get a ratchet or torque wrench on it with a 6" extension, u-joint and 14 mm crow's foot.
I found that the header-to-engine nuts vibrate loose over time, even after torque-ing them a second time after a few days' driving after initial installation. I installed Nord-lock locking washers and haven't had the problem since.
https://www.amazon.com/gp/product/B007VAW3AC
When I reinstalled OEM front LCAs and tie-rod ends to get legal for STX, I used the M12 sized Nord-locks instead of the cotter pins for the castle nuts. They've held up great there too.