Back-up and make sure you are on the right track.....
Are you getting into the right car--parts availability, set-ups from other racers, what car is being run the most there? I'm not trying to talk you out of a kyosho it's a good car.......it's just that a lot of factors go into making the right choice for a first car (I don't count RTR as a first car, my bias). The right answer would be different based on geography alone (my opinion). I personaly bought the wrong car the first time, because I didn't know any better at the time, also the second (when I should have known better).
I think you may be going about this the wrong way, your best source for cheap r/c stuff that has enough quality to be raced are in the hands of your own local racers. If you are planning to race than there must be a track near you. Have you spent time there asking questions and getting to know the racers? They should be the ones to help you in getting your stuff together. At the track I race at most of the more experienced racers step up to help out the rookies that are new to the hobby......(advice, parts, good deals)
Transitioning from rookie to expert is so much more about the help you'll get from good racers than it is about the equipment. You shouldn't miss this opportunity to seek out verteran r/c racers that are willing to help and get to know them. I think the whole problem that you're having now with trying to use an existing pull start motor to save money and avoiding short term costs would be worked out with just a little help.
Regarding the question of starter boxes or pull starts I agree with onnetz 100% about trying to cut cost like you are suggesting, it'll come back to bite you...... your chasing your tail if your trying to make that motor/chassis combo work and you don't know what an SG shaft is.
Any veteran r/c racer that does not see the long term benefits to this hobby of helping out rookies and bringing in fresh people has missed the boat. If you were at my track, and I believed you to be sincere I'd give you one of my last years MT12's and let you borrow my starter box till you could get one.
Best of luck and sorry for being long winded.......