Those bolts and the pin that's holding the clevis to the steering arm of the outdrive, if you want the whole actuator assembly to be able to move freely to get enough space. I guess you already got the pin for the cable out. I'm thinking you should have enough slack in the hydraulic hoses to not have to disconnect them, hopefully.
I think Merc used locking tabs on those big bolts, whereas OMC and Volvo used big cotter pins. I fought with those cotter pins for several hours when I replaced my actuator a couple of months ago. Patience is needed, because access in this job is difficult at best. The bottom bolt, do like I did and put something over the opening of the Y pipe so nothing happens to fall down there lol which can ruin your day!
Do yourself a favor, once you replace the old cable each season, turn the helm to extend the cable out of the guide tube and grease it good with marine grease. I did this every year (owned this boat 19 years so far) and when I disconnected the pins to replace the actuator the cable moved like it was brand new, and I think this is the original 1988 cable!