I think reflexively you can only do 2A in case of the overhead. you really need a superhuman reflex or yomi to do 5C.
and what if it's not an overhead..., 5C will lose to 5B or ragna's 2A/5A if the range is too close.
make them afraid of your dragon punch too, so do that from time to time if you see your enemy is too aggressive to keep them honest. don't DP if they start baiting it though.
use 5D, 2D, DP B/D if they air dash at you.
use DP A whenever they jump away or jump at you during block strings. at close distance if they do a FA Block string ender like dead spike and they thought they are safe you can do dragon punch if they are jumping at you or dashing at you.
just be unpredictable too with your block string so it's harder for them to IB. and most people will do ID only on long recovery move like 5C or 6C. so plan accordingly.