American Motors: 1974 (?) 304 engine vacuum lines, vacuum lines, engine vacuum

Question
I just picked up a '74 304 Hornet hatchback, the valve cover tag codes out to be a '71 engine, is this normal or do you think the engine was changed? Some of the vacuum lines look like they have been cut and plugged coming off the engine, no lines going to the 3 port valve coming of the thermostat housing and no lines to the ports on the air cleaner housing. Although the car runs OK, it does idle a little rough and there is a strong exhaust smell. Are there any vacuum line diagrams available for a '71-'74 304? Thanks

Answer
It is possible the engine has been replaced, it's a simple swap.
As for the vacuum routing, there should be a sticker under the hood showing the hose routing. If not, try this site. It is a 1973 AMC repair manual online: http://www.oldcarmanualproject.com/manuals/AMC/1973/Service/index.html
It also sounds as though you need some carburetor work/adjustment.