Not always, the new type is wider and fits the tabanacle to well.
Try taking the heel off the mast and remove the lead rivet with a large bolt the same size as the rivet so as not to spread the rivet.
Your find the sheaves will be coated with mud and salt, clean off and pass a file across the faces of each one.
Then return to the heel but put the best sheave for the genoa halyard as it takes the most load.
If the screws into the heel are not good and loose, maybe redrill in a new place for a better fit.