340 cam for 318

Nice, like!

It’s only a few degrees larger than a OEM 360 cam. “Small”

Lift has no bearing on any concerns but will certainly aid in power.
The OEM heads flow well to 500 lift. The head can handle it and the engine won’t go down on power.

I hope not! Terrible intake, carb to small

He can get away with another 8-10 degrees @050 easy without ill effect. Been there done this.

Not really. If he had a 318 w/a 2.02, id says yes.
He can use a cam with a LSA around 108 / 107


Not true


As I said above, 216/218@050 can be done. It’s power is just a few hundred rpm off of idle, works with a stock converter, even more so with 4.10’s!

An OEM 4bbl or Performer intake works well here w/a 600 cfm carb.

IMO, any cam under 210@050 is a weeny cam with the gear ratio and intended driving conditions listed by the OP.

PRH and Fishmen gave nice cam recommendations.
i respect your experience and opinion, but i'm only giving my best recommendation based off of the parameters the OP has set.