The 1/2"-20 will work, plus you can get chromed grade 8 allens, use anti seize or very little Thread Lock blue , do not use Stainless Steel Bolts!!!!
1/2-20 CHROME SOCKET HEAD ALLEN BOLTS,(POLISHED CHROME),GRADE 8, BOLTS ARE PARTLEY THREADED UNLESS NOTED AND HEX KEY SIZE IS 3/8.