spinnaker halyard

i just bought a spinnaker and have been flying it on my spare masthead
sheave (below the headstay), which works ok as long as i launch and
retrieve it on the same tack. however i would like to add a real
spinnaker halyard above the headstay. i have a forspar mast with the
sloped top. i looked at steve’s pic of his new masthead and his
forestay tang is different and has a built in crane. anyone added a
crane or know if forespar has a stock item for this? thanks.