Use small round-head straight slot screws along the inner flange of the fender. Don't use pop-rivets. I don't remember if pop-rivets existed in 1953 to 1963, but they were never used on sidescreen TRs except two special ones to secure the VIN (Comm. No.) plate to the bulkhead (firewall).
Use duct tape, electrical tape or similar to hold the tabs to the fender. Put each tab about 1/4" above each hole where you will put a bolt. This way, the tabs will not slide all the way down to the bottom. Get a friend to help. Leave the fenders loose so you don't scratch the paint on the fenders or on the front valance (apron). It's really quite simple to do with a friend.