I need lifters.

if you need them today, check a chain store and have them ordered. Should be there in 2-3 hours if your close to a hub. 340 doesnt need anything special, just hydraulics (if your rockers are stamped) solids (273 style ) are usually special order. Put assembly lube or moly grease on the faces and drop them in run motor dor 20 minutes at ~2500 then up and down a few times. High RPM makes sure the oil gets whipped up there from the crank.