It won't be dirt cheap if they aren't available off the shelf (check out ACL brand, iirc they have the option of a thicker thrust bearing for some engines - iirc minis, so at least check just in case) but you can get material added to bearings, or a thick thrust bearing adapted into place. I've seen it done on vintage cars (for example ones where the material is added direct to the con rod itself and then machined to the required size) - so it is definitely possible

It's not all that surprising that this sort of play develops - generally if it's racing, you've got high rpm, but also typically a higher clamping force pressure plate/clutch setup. And when at idle, there's not much oil flow to the thrust bearing area, and a lot of force to push back against the clutch pressure plate force as you hold the clutch pedal down before launch.

If the rest of the block/bottom end has still got a lot of life left in it, no reason not to pursue it imho.

Whereabouts are you posting from? If you were in melbourne, crankshaft rebuilders in blackburn (used to be in Kew) would almost certainly be able to do this, and more to the point have a top shelf reputation for the qualirty of their workmanship/service.

EDIT - Bige - there's a type in your post (and for the record, it's definitely a typo, I'm not suggesting you can't do math or something!) - the mm should be 26.924 and 27.000 not 29.924 and 27.000 :)