Marty , leave the stock converter in it for now , the converter needs to match the cam , so pointless spending money on a converter that won't suit your new motor when you get around to building it, you can still rebuild the c4 , make sure you put a stage 2 shift kit in it , this will make it shift firmer and quicker and increase the life of the box, i know a very good transmission place , i'm here right now getting new rear unis fitted, joe told me it will cost $1400 to get your c4 rebuilt tough wth stage 2 shift kit , billet servos etc and when you decide to rebuild the motor you can order the right converter for it while the motor is out and just slip it on, you have my number call me if your interested.
cheers chris.