I agree with 4 points... the masthead is very similar to the old catalina's... if you replace anything, replace the sheaves, get rid of that carabiner deal, and relocate the headstay to the inside pin. Put the spinnaker halyard on the forwardmost pin. I suggest you insert a toggle between the pin and the spin halyard block(not like in the picture)... and make sure the block has a swivel connector.
Regarding the sheaves.....the ones you have now are the orignals, which had a channel in the groove to accomodate wire/rope halyards. Before the advent of hi tech line... the wire to rope solution to minize stretch and save space was a normal design. It allowed double and sometimes triple wide sheave placement in the masthead casting.
I am mentioning this because when you put two rope halyards in that space the design may pose some clearance issues.... just check it that they run freely before you step the mast. You can use hi tech rope of a smaller diameter it you want a smoother running setup... Samson Warpspeed is often used in this manner... where the cover is stripped off the section that won't be handled or cleated. The strength of the line is in the core.... so on your 30 footer, you could strip half the 3/8 cover off, leaving the 1/4 inch core to run through the masthead sheaves.
Althought this is a diagram from the Catalina 27, it looks very similar to yours... note the dimensions then check them against yours... good luck.