Actually making the pattern is the easy part. The hard part is cutting out the old bulkhead and then grinding off any tabbing etc. until it is smooth and then grinding any
paint etc off the hull about 12 inches out so that you can glass the new bulkhead in. I am not familair with your boat but replaced a bulkhead on mine last year.
To make a pattern for the new bulkhead I got a large piece of cardboard from an appliance packing box and slowing cut it to fit. Not really very difficult.
Have Fun
Gary