From the Vintage Trek web site. The headbadge is brass, colored with black paint. This badge was used until 1983. It is attached with screws (as in this picture) until 1980 models (or late 79 brazing dates). During 1980 and 1981 the screws were phased out, being replaced with double-stick foam tape, similar to that that used for automotive trim. After 1981 the headbadges were only fastened with the tape.

I finally found a good picture of the short lugs and indeed your bike does not have them.

Edit; also from the from the Vintage Trek web site; Prior to 1982, derailleur cables on Treks were routed above the bottom bracket. According to the 1982 brochure, on the upper level bikes, Model 728 and above, cables were routed below the bottom bracket. On Model 614 and below cables continued to be routed above the bottom bracket. (Some variations to the brochure configurations have been reported.)