A spinnaker halyard block should be attached ahead of the forestay... so you can jibe sail around the outside... rather than tacking it through the foredeck triangle between mast and headstay. Look at your masthead fitting... there's most likely a hole at the very front to pin a swivel block for the halyard.
Besides the products shown below from Catalina Direct... you can also get parts directly from the
Catalina Yachts factory. Call the number at bottom of their website and aske for customer service and/or parts departments. They'll be happy to answer your questions.
Below is a masthead fitting for the Cat 30 that has four sheaves. It would allow you to rig two internal jib halyards forward plus an internal mainsail halyard and a topping lift on the back side... the spinnaker halyard is rigged externally and its block is attached to the masthead casting's forward pin (closest in picture)...
If you need to move the spinnaker block even further forward... to accommodate a bunched up spinnaker sock, or a roller furling upper swivel.. a spinnaker "crane" can be fitted to the front of the mast head casting.
