M_Boats: large genoa

Advice needed, please: I found a used headsail for sale. Dimensions are luff 21'5", leach 20'9", foot 14'11", LP 13'3" -- I calculate that to be a 185 genoa on an M-17. Way too large? Anyone sail with larger than a 160 genoa? All input appreciated. Nick M-17 #69