If you Google a bit, you get many differing lengths for the short alloy head bolts 1" 5/8ths, 13/16"ths(!), 2" and so on. Draganfly even shows a stud in the 67-1114 pic!
Then you get the "waisted" type bolts "suitable for alloy heads" ( my Triumphs have no such bolts..just straight shanks, and do not seem to suffer. Is a "waited bolt" a special chearence in the alloy part?
My estimation is that 1 and 3/4" x 3/8"BSF + washer would be fine...I mention this because I have to have these bolts made up.
Pointers would be of much use. My A7SS is reviving after 40 years as a pile of junk, and is entered in an International Show 10 days from now. Hope to hear.