As far as needing another 5 speed you could make the same argument for suppliers of other parts.
JER.Hill's gearbox is more close ratio. I do not know what Nova's is. For me, the Quaife has the wrong ratios.
I do not have to recoup the cost of designing and building a gearbox over the number I might sell as someone like Nova has to.
I do not see having to design for very early cases with the speedometer drive off the layshaft as practical.
Here are the two options for the bearing plate using the needle/ball combination and a ball bearing:
As I mentioned, the NKIB5903 needle/ball is quite a bit more expensive than the 6303 ball bearing but the 5903 installation is a little cleaner not having to add the support piece for the shift shaft.
Any opinions on whether to go cost or clean?
Either case requires a retainer plate on the end of the layshaft to lock the shaft to the bearing. This makes incorporating an oil pump onto the end a little more tricky but still possible.