It seems to me that the best "bang for your buck" is to do a quality rebuild of your existing components. Add to that good quality shocks, springs and a good alignment and you will be amazed at what a difference it will make. Also a good steering box, very important. (don't forget the rag joint and subframe bushings, all of it makes a difference)
I have no experience with Delrin bushings yet, but since you stated you will be driving on the street most of the time I wanted to tell you I have read and been told that the Delrin bushings DO transmit A LOT more harshness from the road. If you want to keep your ride quality good there MAY be a better choice.
I am NOT an expert on this. Just my .02.
Good luck with what ever you decide.
