suggestions for my 340?

My recommendation, as it doesn't sound like you've done a lot of work on carbureted/pre-computer cars is to start with tuning.

Modern cars do so much without any interaction from the driver or a mechanic, it's easy to forget about this stuff.

Start with the ignition timing. Judging from the orange box (ECU) on the fender, I'd say that it's probably an unmodified distributor with a stock ignition curve. Your engine would probably benefit greatly from a recurved distributor with higher initial advance and a faster curve. I'd also toss the orange box for a chrome box as the orange ones tend to be a little flaky.

I'm betting that the carburetor is pretty much untouched as well, but I know very little about Edelbrock carbs, so I won't start to try to give advice on tuning it. I'd leave it alone at this point and work on the ignition first.

There is a lot of info on this site as far as ignition tuning, do a search and you should be able to find instructions to set it up.

Start with the basic stuff first, you'll also learn a lot about how the systems work in the tuning process.