indy lax heads for mild 318

They make sense if you want more hp.
318 heads were designed for the 273 which give a good cfm per cid ratio for that engine.
340 has about the same cfm per cid ratio that's why those engine can rev cause they can breath. 318 and 360 got short changed in the head department.

The Indy heads will flow more than fully ported 2.02 318 heads and especially just valves and a little bowl work.

With the Indy heads you'll pick up about 75 cfm. Even with your mild cam you should at least pick up 1 hp per cfm 75 hp. And I'll bet very little impact down low. It's better to build up with head flow than cam for a streetable engine. That's why LS and Hemi have such high flow cylinder heads.

There's a guy on here with a 340 with stock cam and edlebrock heads that dyno 400hp which will be way more streetable than large cam stock headed 400hp 340.