On the Tunneys Pasture end of the line, there are currently two options being looked at: One which builds a large station on federal land (their co-operation is needed); and one with the bus stops along Scott.

I have high-lighted the bus stops in yellow.
There is a preference for the first option since it provides room for the estimated 20 bus lay-up spaces which will be needed.
Notice that both options suggest lengthening the bus ramp. This would require partially filling in the trench. This fill would then need to be removed when the rail was extended west.
To the east of Tunneys there would be a dedicated bus Transitway. This might be along the old rail RoW, or new transit lanes taken from the general traffic lanes of Scott.
If, for Option 2, there is not enough space for the required stops along Scott to be to the east of the transit bridge, the Busway would be extended to Westboro since buses would be past the Transitway access point at Tunneys. The rail would not be extended to Westboro. The section of existing Transitway between Tunneys and Westboro could still be used for some buses and the rest would be on the new busway along Scott.
Conversely, I would have suggested that the rail and Transitway IS extended to Westboro.
This would allow for a simpler bus ramp which would not be in the way later (OK, I have assumed a Byron route starting from Churchill.

If a Parkway route is used, the ramp would need to be removed.), and distribute the transfer load a bit. Also, the #2 bus is diverted from Richmond Road to allow people to transfer to the Transitway at Westboro. This makes sense if the train goes to Westboro, but not if people must transfer to a bus and then transfer to the train one stop later.
The general station layout I am envisioning is
(Actually, the East-bound pick-up area might be moved east of the loop so riders could actually be picked up by a bus leaving the lay-up area.

)
This same general idea is easily transferred back to the Tunneys Station.
Notice I have included space for bus lay-up although it could still happen at Bayview instead of Tunneys.