Here's your opportunity to make your boat unique and very functional. Build-in coolers, tables, storage compartments etc... take a good look at what is out there and then get a good upholstery guy on board and start building... Use 1/4 plywood for the coaming templates and build the seat structure out of 3/4" marine plywood. Keep in mind that wood rots and try and keep it off the floor for drainage and air circulation. Some nice aluminum brackets will work nicely. Most salvage yard boats are going to be destroyed and of little benefit to you.
I would be tempted to mount four buckets in the cockpit with an engine cover and a seat on either side with coolers built-in below. Have a table mount in the center of the buckets so you can rotate all the buckets to "sit" at the table.
Get out a tape, make a sketch of the area you have and post it here, we'll help you
