The comp 252 is damneer a dead ringer for a stock 360-2bbl replacement cam. The 252 has 0.015" more lift/ every other spec between them, is dead nuts IDENTICAL in every way.
The last time I put a mild cam in a 318 it was a Melling 360-2 stock replacement grind. Yes it made a difference. Very noticeable gains. Dead stock smooth idle, 19" vacuum, great mileage and power was much improved. This was in an 83 D250 with untouched stock short block, untouched stock 727 and converter, 3.55s, and tall/skinny 235/8516, 10 plus. I added a performer (not rpm version) intake and carb, and hooker super comp headers at the same time as the cam, and a set of EQ 318 B heads. I am about to do the same with the 318 in my 78 Fury. No headers, and a set of machine shop fresh '302 casting closed chamber heads. This Fury isn't as heavy as the truck was,
And has a stock 904, with 2.71 gears and 5" shorter tires than the truck had (225/70-15 cooper cobras on the Fury) have either an Offy intake or another Performer to choose from on hand, as well as one of 2 fresh "Demon sizzler" TQs on hand, a 500 CFM AFB and a 600/625 comm AFB to choose between, on hand for the Fury's 318.
My fury actually don't run half bad and mileage is fantastic as is, and it even still runs it's original lean burn...
I just want *a little bit more" out of it.