truck wont start

[Blue_71]

ok-- truck was running good, missing slightly, plugs were gettnig old though and i need valve seals so thats understandable... a friend of mine let me have a carb that was running good on his truck, and i put it on because it had a working choke, well, it did start easier... was flooding bad though and i had it sitting on a hill so i moved it so i could adjust the carb. after i moved it, it started missing even worse and i had to put it in 4-lo and low to even move. it was popping bad and you could floor it and it wouldnt rev up any. well, i finally got it to a good spot and stopped it, shut it off, the next morning i checked and the mixture screws were out 6.5 and 7.5 turns (this is a weber-wanna-be-edelbrock) i turned them in, and it wont even fire... ok, carb is screwed up, put the holley back on. still wont start... check for gas, its getting gas, check for spark, its getting spark, but it wont even fire so whats wrong with this thing??
(sorry for th elong post)

btw--- this is my 71 K20