340 Cam Kits which ones work with a stock block

yep
squeezing down the LCA gives the choppy idle - more duration more chop
but also plug fouling and harder to tune the carb
more lift (or more duration @200 with a rolled over nose if lower lift is desired) gives more power
early intake close is must with low compression
if you want it driveable- big seat duration makes it mostly strip only with low compression- loose converter and low gears

the recollections above about durations of DC cams seems close
The seat durations varied more than the .050 depending on what vintage and who was grinding the cams
I think the early ones were Camcraft- I talked to the master maker many years ago-knowledgable
touched them up with a file and stone just like I saw Potvin's Bill Jenks do in the 70s I think they were doing the masters for production cams too