I've been watching this thread for awhile as I am your size plus 10lbs and own a 2014 SJ and think I could help. Heres my thoughts...
1) If you're lacking in the balance/coordination department, throw some blowsion destroyers on there. My buddy had those on a 2012 and it made it super stable, carved like a razor, etc. I wouldn't say I would need them, but if you want to make it stable that is a must. Double tubbies for the win!
2) if you think you have decent balance/coordination, just get some zero degree bars and tray time. When I first came over from an 08 SXR to SJs, I thought they were unstable too, mainly the 91-07 superjets. I always thought these 08 plus ones were like a mini SXR.
3) As far as better steering, I have read there is a ton to do. Old style steering cable, relocate ball on the nozzle, etc. I plan on relocating the ball on the nozzle. I think being bigger we can throw the skis around better, but the steering mods would help.
4) I and many others think the stock plate is just fine, if you're going to do anything cut it flush with the hull.
5) I think the stock pole is fine. it is already -2 and they are pretty strong. i will eventually replace mine, but it is money wasted to me right now. Especially if you are just goofing off with the SJ, I doubt you will be breaking it anytime soon.
6) replace crappy plastic intake grate
My recommendations for you:
-tubbies ONLY if you think you need them
-Zero degree bars
-Cut ride plate
-Steering mods
-Tray time!!!
-intake grate (tons of options)
Save your money and don't blow a ton of money if you are just goofing off with the ski. Use that money for gas/oil and ride the poop out of it. People will tell you to buy all this stuff and in the end the best thing you could have done was spent money on gas and oil and riding!