No worries. Hopefully it can save someone a few headaches if they ever come across this issue.
I received the new synchro, springs & keys and got set up and ready to re-assemble. Unfortunately I realised the synchro hub needs to be changed as well.
The new 3 piece synchro on the 2nd gear side (33367 in the above diagram) has a different design, with tabs in the center which lock into the face of the synchro hub.
I didn't pick this up, and when checking part numbers, the image shown on the website shows the opposite side, which looks the same as the original part I have. Also, I did not realise there is a recess for the springs to mount in. Luckily I noticed this before I pressed the hub all the way on.
So the new part required is "Hub transmission clutch No. 1" Part number 33361-71010.
You can barely see the recess for the springs in the above image. This is what led me to believe this is the same as the part I have.
Here is a better look at it.
And here is the recessed face required for the synchro to locate in.
