suggestions for my 340?

There is a shorty headers, so there is another option. If it were me and on a budget, find out the rear ratio, pull the timing cover, see what cam is in there and go from there. If it's an aftermarket one bigger than stock, get the cam card and degree it in. Post what it is here and folks can advise on advancing or retarding it based on what it is and your use, gear, trans etc. Buy an intake and carb accordingly. If the cam is small, stick to a performer and 600cfm, if larger, then again, seek advice. Compression is your biggest stumbling block and a large cam will be a dog and even more so without the correct converter.

Also, hows the tune? There maybe some HP on the table with some added timing and carb work.