340 Cam Kits which ones work with a stock block

Crane Z-268-2 is one decent choice. A bit milder than other 268's.
Not aggressive ramps so not a cam to tend to have issues. Will work well with a lower stall converter. My son's 340 has a 2200 RPM stall and this cam just motors right out from a stop.
But I am not impressed with the hydraulic flat lifters being used these days. See the thread on lifters running at this time.