Herre is some rough guidance to get you started....
For an asymmetric
or symmetrical spinnaker
on a cat I like the sail luff to be two or three feet shorter than the length from the prodder or bow attachment point to the hoist pulley on the mast
. With this dimension the tack of the sail when flying will end up 6 to 8 feet above the deck
giving good visibility ahead under the sail. So for your boat 53 -3 = 50 feet.
For a symmetrical spinnaker starting point let the foot of the sail be about half the luff distance above. So (53-3) * (53-3)/2 * 0.8 form factor = around 1000 sq ft.
For an asymmetrical to fit nicely the clew location must be placed so there is a fair lead to the sheet block. Sail makers will have nice modeling software
to help with this. You can use trigonometry to get a starting point.
Without doing any math I am thinking your boat could carry around 1000 to 1500 sqft total in an assyemtrical. For carrying in higher wind offshore
I would want a second smaller spinnaker with a slightly shorter luff and much narrower foot, the net result being say 600 to 1000 sqft max.
Hopefully this will get you started in the right direction. Consulting a sail maker could be very beneficial in getting a sail that will fly nicely.