Adding +1 fork tubes, HD springs, and an Ishock at the rear will give you more ground clearance for cornering -keep you from constantly scraping the pegs. Which in turn will keep you from crashing as much -don't ask me how I know that :roll:
I'm used to road racing, so I really miss the stopping power of a front disc. Might want to consider that as well.
Plus, in my opinion, these bikes are just way too slow without an 88 kit. I'd recommend the TB88 kit.(cheap)
Change the gearing and add some pirelli SL26 tires and you should be set.
I would recommend the TB88 kit. Good buy for the $$$. Get your bar kit, whatever you want. Front +1 fork legs with HD springs, and some way to bring the rear up a little too (swingarm/shock combo or just longer shock - depending on your budget). If you are just doing a small indoor kart track, then you are not going to be getting the speeds of an outdoor one, so you can probably wait on a front disk and spend the cash on other things. Maybe look into 1.6" rims so you can use a little wider tire properly and put a little bigger footprint of rubber on the ground.
...of course you can really go crazy too. I am sure you will eventually.
I would definitely raise the bike up with the +1 fork legs and stiffer springs and either a longer rear shock or the stiffer spring and the shock link that raises the rear. That will get you the ground clearance that is so important. You might want to look into some of the front end kits that include the front disc brake, that is a big improvement. The longer swingarm will help too, but make sure you get a shock that works with the swingarm. The high bars are a must at your size (no offense, I am 6'2" 220lbs) to keep you from catching a knee and wrecking. I wouldn't worry about wider rims until you have enough horsepower to need wider tires. I would run the Dunlop TT91 80/90 tires unless you are going more than 88cc. You will definitely want more power, but that depends on budget. You can spend from a couple hundred to 5000.
I would get plus ones with medium to heavy springs, I run a Romic rear shock because it has adjustable rebound. It works really well for road racing. you will probably be fine with drum brakes, and you can always go to better pads. I am on stock drums and pads and the bike stops great! My buddy just installed a five o front disc kit and the thing absolutely SUCKS. I was messing with him for a while saying he should be out braking me but after riding the bike I see why, the thing sucks. But on the other hand my other friend has the bombshell setup with disc and it stops pretty hard, the only thing I don't like about it is that it is either on or off. There is no in-between. I run the TB with gearing and the bike hauls. I would stick with the stock swing arm though, I installed a sano swing arm last week and I didn't really like it at the track, I am getting used to it but it just doesn't turn as quick because it is longer now, so I have to lean the bike WAY more so I am scraping peg a lot.
Sounds like you have your mind made up. I would stick to the plus one forks and ishock plan. You dont want a ton of travel and ground clearance for riding on the road. Bar kit, Plus one forks with springs, Ishock (nice for future upgrades like an extended swingarm), and a BBK and you should be all set with a smile from ear to ear.