Is there a glass kit for this engine?
Yes, Walthers makes a detail kit for the Athearn F7 that includes grab irons. There are enough parts in one kit to complete an A-B set. I just picked up 2 at my LHS.
The Walthers F unit dress up kit, 933-822, has grab irons and glass for the Athearn F7–
http://www.walthers.com/exec/productinfo/933-822
American Model Builders has a two laser-cut glass kit, 152-228 and -229–
http://www.walthers.com/exec/search?manu=152&split=30&start=90
The 229 will fit as is, whereas the 228 is designed to make up for the Athearn shell.
There may be others; these are the ones I’ve tried.
Athearn now makes the “glass” for the F7. Check www.Athearn.com and check the parts listing. The part number is 11016.