1974 Dodge Van

Nope. Two totally different animals. The 360 is a small block and is common to the old 273, 318, and 340. Besides the pistons, the only difference with the 360 is a crankshaft has larger diameter journals.

340s had high flow heads. The '68 - 71 340 heads are very desirable and valuable because they had bigger valves. Your 360 has the same heads as far as the runners are concerned, and the seats can be ground out and the larger valves installed from the early 340s. At that point, you will have a very valuable set of heads.

Even the highly sought after 340 can be easily matched by the more common 360 by modifying the heads. I have one sitting in a '73 Challenger behind my house right now.

Caradiodoc