340 six pak setup

Picked up a edelbrock 3x2 set up at Carlisle past Sunday
Question. 70 FSM has zero info on 340 6 pak I know the text info for the 440 6 pak is a good guide and probably identical to the 340
But where can I get the specifications Holley 2 bbl carbs
Front / rear. R4789. R4790
Also the center carb is a R4782
Date code 2460. =. 9/3/70
So it's a 71 carb
But not listed in FSM. or The white guide books by Galen G
Any info appreciated
Thanks
back in like the mid 70''s you could buy NOS 6-pak manifold and carbs for like $300. no hdwe, but the real deal otherwise. I still have some of the old parts for sale sheets. I think they were from Couch, or Gratiot. You could by NOS avs''s for $19.95. New Holley 500cfm 2bbls for $29.95. Complete engine overhaul gasket kits for $9.95. Used cone clutch sure-grips for $20. Stuff like that, typed, single-spaced on both sides of letter size paper. They were like a disposal company for overstock, discontinued parts from the big 3, and their vendor-suppliers.