I am into some bluegrass as well and I have to confess that I did this too......with my 68 dart.
The dart makes it easier because it does not have a tail panel in the way.....because when you open the deck lid where the tail panel is on your goes up with the deck lid.
But yea, I hauled a 360 short block to C. Springs and used bungee cords to keep the lid down because it didn't shut all the way with an engine in there LOL