340 Rebuild "Musts"

Bore n hone , try for 4.060/.020 over, torque plate if available, if not don't sweat it.
Rods resized and either have the bolts stretch tested or better yet buy new ones, don't have to be arp, pioneer makes some cheaper builder bolts.
if the crank main/rods journals polish up, great, if not... just have the Mains ground .010 under and rods .020 under, since you say they are grooved and .010/std. Balance job a must, and try some hasting moly rings or perfect circle...kb243 pistons are great. If you can afford a square decking of block...go for it, if not...at lease have it cut .003 on each side.
Heads need a good 3 angle, guides, hard seats if regrinding stock valves to re use. When you pick a cam, the springs you need will follow.
Timing chain can be optional billet aluminum or you can simply run a 45 dollar chain and use bushings to dial the cam in...I'd buy a billet set.