While pricing a new cam - the DC engine book says I need these springs.

Find out the specs for that spring and then go to an aftermarket manufacturer and get one to match (or in that ballpark)...

Also: Word of caution, we installed the 273 rockers on a 340 and I had to grind some clearance where the rocker hit the spring a little bit... Mock it up and check your set-up... Not a show stopper, but it's good to grind a little to get clearance to the spring...

A quick hit on a bench grinder will do it...