Go high or go low? 3C would be NF, 3H would be a splinter, 4C was undiscussed but is presumably better than 3C. If it makes any difference, the 1C bidder might bid a slightly offshape NT here with heart stoppers, so you can presume they are unbalanced or stopperless. It's extremely rare that X isn't 5-7 at this low a level unless responder is perfect t/o shape.
Edit: quick statement clarification in description. Also, this is from an outside source, in case it seems familiar, but I'm interested in what other precision pairs would do in this situation.

Help

1♣-1♥-X-P
2♣-P-?
1♣: 16+ art
X: Usually 5-7, but could be GF if no better bid
2♣: nat 5+ suit, f1rd