Hi I did this project last year - although I hired a professional to replace the mounts, I have taken the bulkhead off a couple times, no issues to do that...there's a post I did in 2017 when I cut a hole to do an approved Catalina modification to give space separation from the exhaust heat riser elbow.
I stayed and watched the mechanic do the entire job over several days. Those motor mounts are pricey - yes I got the Universal mounts from Catalina Direct.
It was suggested to cut and place an access panel to access the port side but it's not necessary. You will hoist up the motor anyway to replace the mounts. I also replaced the prop shaft, cutlass bearing, and stuffing box at the same time (again parts from Catalina Direct). Might as well do these major projects at the same time because you'll have to realign everything with new motor mounts; this is the part where having an experienced pro do the alignment makes a huge difference - way beyond my scope of ability.
I also replaced the heat riser elbow, all hoses, and the heat exchanger (I bought one years ago knowing parts were skyrocketing in price so just had it ready, in storage) - might as well as you'll never have better access as when the bulkhead is off, and the motor hoisted. I also rebuilt the water pump (replaced bearings etc. at home).
