If it has a welded lug, then it is mid 78 or earlier. ALL the Bastian built frames had the welded lug up until Scot (OM) started making SE frames (built at Race Inc by Bastian). At this point Scott contracted Alcoa to make a one piece (unwelded) lug and all the Bastian built frames from then on had the unwelded lug.
Like Pep said, let's see a picture. Welded Lug with FMF drops is one thing BUT does it have the short or long seat stay gusset and does it have a brake bridge?
GR8, It kinda freaks me out that you named my bike

, but yes if I show, I will have it with me.
As far as the GTO. PLEASE step away. I very rarely put water on that car.