That was my next question. Could I try and fit a different year or different model.
Yeah. You could try 80-95 1/2 ton 2WD headers like Hedman Elites (Jeg's PN 500-89358).. there's no guarantee that they will fit though. They're 3/4 length according to the catalog's image.
The 351W has a one-inch taller deck height and is slightly wider than a 302. If you can fab, then order a set for a 302 for your year, extend the primaries, and maybe angle them to compensate for the increase in width. Your auto trans makes things a bit easier since there are no linkages to deal with.
I did a search in the 73-79 forum for "351 headers" and came up with 17 pages of hits. A quick scan of the results indicated some fellow FTE'ers went with shorties.
Same issue w/ 65 did not come with a 302; understand chassis same/simular 65-78, found Hooker longtube worked. Had to lift passenger side slightly to get the header around the starter. In addition, used 4 1/2" grinder to remove small amount of metal on passenger side engine crossmember I wanted additional clearance for header flange. Seem to recall thread on simular topic, believe member mentioning the 351w will set slightly higher than the 302. Not sure about shorties. Just had exhaust system installed found experienced shop can install for just about any application. Anyhow, food for thought.