need advice on what cam , springs and things to get for my 340

wel i guess i live in an alternate universe as my old 340 got 20- 22 mpg on the highway all day and it made 425 hp had 11.2 compression and 190 cyl pressure . never got a good et because it would spin through 2nd gear best et was 13.6 ay 103 mph . but i no longer race so don't give a f about et