hey dont forget that the solinoids need to be rebuilt after so many uses (cant rember the recomended interval). so if you do go with a used kit factor in rebuilding the solinoids.
I'm building a nitrous set up and its gonna be over 1K,nitrous kit-388,1 gal cell underhood mounted-96,holley blue and regulator-130,window switch-130,msd box with timing retard-288,bottle heater-119,purge-106,thats over 1200 plus shipping,doing nitrous right is expensive,and to get 10lb bottle filled its $40 here. Edit-Also nitrous pressure gauge and fuel pressure gauges are needed(But already have those).I hate hobbs switchs i've had 1 screw up on me and alot of friends have had them mess up,just watch ya fuel pressure gauge.
Even though I'm probably gonna be down about 1K after I have the nitrous in this motor it'll be a nice setup to run for a while. I can always move everything over to the 331. I figure it's a fun hobby, beats collecting stamps or barby dolls . . . PS: no offense to Bryant and his barby doll collection