picked up a 340 long block w/out specs

roller cam?
you need to lube lobes on a FT
so do the compression check
pull the intake and inspect (has intake been open to the dirt?)
you can degree the cam and see what it is
what do the valves springs looklike? duals? you could bull one and check and check retainers and keepers what quality
put a 4bbl intake on it and pre lube
fire it up
if it has never been fired up and we have no idea how long it's been sitting you do not want to start dry
you might get away with it on a junk yard take out but not here