The 60 series five speed was a standard fitment in some US models, so I presume that parts to service these transmissions will be much less difficult to locate there & hopefully, much less expensive.
Keep in mind that Bluemax lives in the US.

I have not yet done a rebuild on the five speed, but I hope to be able to ship my 56A box off to Ferral within the next month or so. Yes, I have braced myself for a bill that reflects the rarity of a thirty something year old gearbox overhaul, particularly when the box & all the parts for it were never sold here.
To add to the financial burden, I hope to make some changes to it if we can source the right parts, & that may involve the purchase of one or even two damaged gearboxes if they are available.
It's only money.

Boofhead is absolutely right, the 'proper' five speeds are fantastic to drive, particularly on a winding road in the hills where you can keep the engine right in the power band. It's a great feeling.