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I disagree that taking a bus beats a car, but no matter, since OP said they are taking the bus. Driving between parks especially where RD is concerned, is MUCH faster than waiting for buses to arrive!
If the TSM FP is important, then be sure to leave AK (as in be at the HS bus stop) no later than 10:30am. This is assuming you are NOT trying to do this on a holiday week. Taking a cab could also help.
It is important to note if the day you want to do this is a morning EMH day or not. If it is EMH, and you arrive at 9am, then you might find a healthy wait at the safari when you arrive. Either way, the line for the safari often builds fairly quickly....but PW line stays pretty short most days. Unless it is in rehab during your trip, as another poster suggested.
In short, the time of day you plan to hop isn't a popular time. You would probably do well to consider a cab or face slow transportation.
To use you TSM FP, all you have to do is arrive at TSM by the end of your time window, but don't expect mercy if you show up past 12:35, especially for TSM. The CM's there are strict. Also, remember TSM is towards the back of the park.
We once went to AK for just the EMH hour.
We left the park before 9am, and did not get to GF for a 10:40am ADR- the bus took that long!
More recently, we combined Test Track and TSM FP's. Trust me, it is LONG walk from the exit of TT to the entrance of TSM!

Our FP window started JUST as we entered the car design room of TT- we were nearly first out of the design room, and the line between the design room and the ride was short at 10am. As soon as we got off TT- we jogged at least half the way to TSM- and BARELY made it before our FP expired, and we did not have to do bag check.
If you are talking about doing this on a holiday week, then I'd allow an even bigger time window for the transfer.