9/16 studs are scarce as a chicken with lips, and E$$$$PENSIVE. There's really no need for the extra clamping power of a stud, and even a modified stovebolt engine probably won't be dismantled often enough to justify saving the threads in the block by doing a one time installation of a stud. Our round track engines got refreshed every 1K miles or less, (if they didn't hand grenade first) so wear on block threads was definitely an issue there. I do plan to run studs on the cylinder head, since the extra displacement (30 cubic inches +/- a little) will raise the compression noticeably.
Jerry