318 strokers are pretty cheap to build. You can buy a 318 rebuild kit off ebay for $169ish plus shipping. Comes with rings, bearings, gaskets, pistons, and everything else. Northen Auto also has similiar kits at similiar prices that'll get you everything including a performance cam and lifter set. Machine work to turn a 318 into a 340 stroker(318 with 360 crank) is about $250 in my area plus boring if need be. This includes turning down the crank and rebalancing the rotating assembly. So youre looking at less than $500 for a completely rebuilt motor that comes in at just under 340 inches. Mopar Muscle just did a 'teen rebuild and it ran them right around 1000 bucks. If youve got a budget and a little know-how, its not very hard or expensive and makes a nice little combo!