I'm well into my small block 318 to 340 swap. The almost complete 1968 340 cost me $1,000, the cheapest rebuild cost another $2,800, the 340 motor mounts $50, carb rebuild maybe another $150, excellent original exhaust manifolds $650, 90 degree oil filter adapter $50, 26" radiator $75, fan shroud $75, clutch fan $100, new cap, rotor, plug wires, plugs maybe $150 (and you will need an electronic distributor as well), plus $ for a starter, radiator hoses, heater hoses, bypass hose, water pump, power steering unit, alternator and I'm sure there are more parts I am forgetting such as an air filter set up and the rest of the exhaust system. To go the 340 route is expensive, so if a 360 will do, I would definately suggest shopping on your local craigslist to hopefully find a motor that is still in a vehicle running that does not need the rebuild (check the compression). As noted above, watch out for cracked blocks and ones that have been bored out as far as they will go.
Charlie
70 Challenger