take pictures-- to assist yourself-- your swap sounds pretty straight forward-- a 318 for a 340-- you should have all the parts already at your disposal.
not sure if the cars wheel base are the same, if so- your donor car has the drive shaft you need (8.25 vs 7.25)
if both sets of rear springs are the same (used)--- leave the rears attached & unbolt the rear shackle & the front mount-- then roll the assembly out/in-- much easier than lifting!!
Lawrence