I like the fact that you have been offered help instead of someone trashing your work. This is what makes this such a great forum. I also need to get the Yost Videos.
Just compare the doors to the 1966 Johan kit .That would be the proper Hearse for a 68 . That kit was based on the Miller Meteor body .Just like the one we took to Florida for spring break back in 87 and 88 . It is a good model of that car we drove , except the back window panels on my buddies car could be removed for the ambulance use.
Look on line for a piece of formica or the local kitchen place could give you a place to buy it . You could get a different color standard pick guard. Just glue it to some copper , aluminum ,steel or stainless sheet.