If your on the cheap, 360 all the way. Later on in life when you got your chit in one bag, you could scout a 340, but just for the nostalgia. Sure the 340 has its points, but all those can be made into a 360 build too. It mainly had higher compression, tighter rapping and larger valves, put those heads on a 360 and there is 1 mark crossed off. put decent pistons in a 360 and there is #2. There is more street muscle to be had in torque, and a longer stroke can produce more torque because the "lever" is longer due to its crank stroke. The 340 can rev higher because it has less centripital mass, ie, the rods are closer to the centerline of the cam, and can be stroke out more than a 360 due to the larger cylinder size, but you sure pay for those little tidbits. Last but not least, every 340 block you can afford is at least 38 years old, 360 blocks can be found up until 2002 and can be found already set up for a roller cam and had better flowing heads than a 340 even with their larger valves. My vote is for a 360, and I have owned 3 340's. Liked them all, but the 360 has 20 more cubes and more torque. Keep the 340 for the resto crowd...
