Definitely have some tuning to do, you should be getting closer to double that for mileage.
For reference, the 340 in my Duster is a '68 340, .060" over, 9.8:1 compression with 308 heads, 2.02/1.60 valves, 65 cc's chambers, stage II ported and flowing 264 cfm at .500", it has a Lunati 60404...