Probably all chain is going to be your best bet. You are correct that there is not enough "fall" in the C dory 25 to use a vertical windlass--all chain is probably the best--maybe 100 feet of 8 plait, and then 150 of chain. One of the dealers on the East Coast outfitted their 25's with 150 feet of chain, to get more weight in the bow. That has some disadvantages, in that it can cause bow steering in steep seas from behind, as the boat tends to broach.
Because of this, I have only used horizontal axis windlass on the C Dorys. Other larger boats, I have used a vertical axis, but with 400 feet of line and 200 feet of chain, and a "fall" of over 5 feet.