360 Date Coding

Look on the oppisite side of the block where you found those numbers and there you should find the date of casting. If they are 340 heads i believe they would either be a J head or an X heads. X heads would come with the 2.02 valves and the J's would come with the 1.88 which can be worked out to fit the 2.02 valves. With a little port work and gasket matching they can can be made to run very well. on the inside of the head it will have a large J or a large X on it under the rockers. Look at that date casting on the block and report back.
Small Block