Hello everybody from italy , still here and working on my fastback issue ... and seems neverending .
Moved to edelbrock 500 , with adjusting kit is real easy tune it up , also who has low  apprentice on carbs . 
Basically is ok , still miss some on high rev but , no smell , no bogs , and backire  i can be satisfied . 
The winterproject  ended moving the 3.80 for a 3.40 ( with t5z)   and take a ride just around the block .  It's really better also if i haven't speed enough just to brake in the gears . I can hear some repetitive noise coming from unknow point ...
Before all this mess , i do resurface the flywheel ( not did at clutch change ) also to remove clutch chatter .
Not seem the solution cause clutch still chatter ...At this point i don't know what more i can do . 
Have also balanced the driveshft with new universal joint . 
Before mount everything i take a look at axels spline and seems not in good shape . Tops of spine are coming more thin , sharp . 
My question is this : how i can check worn out spline ?  
What i have observed once mount all in place is the freeplay of rear wheel between gears ticking , 
If zero is my 12 o clock   i can move wheel at 12: 05  / 12:10  before gears touching . 
Take note that with new backlash at 0,006 inch ( the lowest suggested ) , adding oil , seems there is no freeplay between ring and pinion . 
I have LSD diff  with planetary gears , no clutch  so i can imagine there is some freeplay also there .
Hope to be clear and suggestion are welcome . 
Thanks Alessandro