340 Vs 360

There is no "versus" here. Both are a great option! If you don't have a motor, there is no need to go 340 simply because they are usually much higher priced. The 360 is very easy to get in great running condition, and offers loads of performance. The cam, heads, intake and rods all interchange with 318, 340 and 360. Also, if your just going to do the "mild head and cam" upgrade, my money would be on the 360 anyways, as I've built both. But should you happen to come by a cheap 340 in good shape, by all means jump on it. The real story here is you can't make a bad choice.