I've posted this over at the tri-five forums and still looking for some ideas. Car is a '57 with late one piece seal crate engine, new front mounts, new bell housing mounts, new CPP cross member. Car was an automatic originally but was swapped over when I bought it but looks to have new linkage parts, has original GM 3704922 cast bell housing (which I've centered just recently), Hayes flywheel, Mcleod diaphragm clutch, Mcleod 5 speed. It chattered with prior Saginaw trans (video's) and still does it with new 5 speed trans. I've included these 3 video's for you to see what I'm talking about. It will do it when you just release clutch, and I mean a light release before engagement...it will render it's ugly head sometimes on down shift to 2nd gear. The only thing I haven't changed is the fork and linkage it was in car when I bought it
https://vimeo.com/129837265
https://vimeo.com/129837264
https://vimeo.com/129837262