1971 c10 questions.. Vac lines, Carbs, and passing gear linkage

[79underconstruction]

Hey guys been a long time since i been on here. hope everyone is doing great. So i just picked up a 71 pickup. it has a 350 out of a 73 chevy in it. it has a weber carb on it the people i got it form said they dont know if its a 600 or 750 . Wondering if anyone knew how to figure out which it is? Also the truck runs great but will sometimes it will start to run rough and die.. starts right back up.. Im thinking the carb is dumping too much gas and flooding itsself out? also on the tranny which i think its the th350 the passing gear linkage isnt hooked up its just hanging and the mount is not mounted to anything.. can anyone describe or have pics of where and how to mount this and hook it up?

also any diagrams of how the vacc lines should be ran? My brother told me that the tranny is run off vac lines and if theres not enough vac pressure it wont shift just right and someitmes the truck is hard going into reverse or shifting from 1st to 2nd it will slip for s second before shifting.

I will be taking some pictures soon and i will post them. I plan to clean up the truck straighten the body up and repaint to match a 1963 algo tarvel trailer i restored.

Any help will be much appreciated guys thanks!