Correct, early '81 1.6L had 11mm Allen-head bolts. Supposedly the gassers' ARP kit will work with them. I'll find out in a few days.
ARP part #sHead Studs..........................251-4701Main Studs...........................204-5402Con Rod bolts 1.6 and 1.7......104-6002Trans ring gear bolt kit 020 ...204-3001Oil pump bolts.......................661-1014 I assume the head stud # is the 12mm stud. Some 1.6's had 11mm I guess.