Walter,
If it were my car I would install them. The buffers help locate the hight of the trunk lid with the rear panel and also help keep it centered and not chip/hit the sides of the channel when closing it. The trunk hinges are just adequate and are easily sprung/bent and the buffers are insurance. You say it is not drilled for them? Have they been filled in? Look on the inside bottom edge of the lip for where they might have been filled.