Edelbrock LD4B

In part 1 of the article mentioned above, with a cam change on a stock motor they got an STR-12 and 2 Holley 600s to put out 450 hp at 6750 rpms, and in part 2 (Sept '69 Hot Rod) they got a modified 340with the STR-12 and 2 600s to put out 487 hp at 6750. Not bad for 1969 technology with a motor that had only been around a year.

That same article compared the LD4B and an LD340 on the 340, and the LD340 was worth an additional 15 to 30 hp between 4500 and 5000 rpms on the same motor. In the spirit of this thread, the LD340 would not work well on the smaller port 318/273 heads, unless you port matched the heads to the manifold.