gofeversailor - the answer to yor two questions are:  the newer shrouds are shorter than the old, and  the most expeditious fix for this problem is to return the shrouds for a refund and order new ones from Murrays (1-800-786-7245) or some other marine place. The wire length for the shrouds on an older H16 are 1/8 1X19 19ft. 1/4 inch. 2each. Double swaged is best. Coated wires [black or white] is optional.
Before you order a new pair I think it's best to check your forestay, bridle wires, trap wires, and the wire that runs through your jib. Also, unscrew your anchor bolts and check for corrosion.
Keep it safe, Keep it simple, and Have Fun!!!