You can get a screwdriver bit socket set to use with a torque wrench. As you found out during removal, exhaust cover screws can get pretty tight over the years and are easy to break off. If you have to remove them in the future, the internal hex on allen head screws may simply round off before you can get them to budge loose.
https://www.amazon.com/Craftsman-Piece-Drive-Screwdriver-Socket/dp/B01JSZREFG
There may be other issues causing your leaks so let’s see if some of the real veterans weigh in on this.
Bob
1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1957 Evinrude 3022
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20
1982 Evinrude 25hp
“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."
