Anybody done this and able to comment on their high-speed driveability (cruising specifically)?

Internet calculators suggest my 0.870 5th + 4.9FD = 4,000rpm @ 100km/hour.

Wondering if its worth considering sourcing a B18A 5th gear which is 0.717 and supposedly equates to 3,300rpm.


So, any personal experiences?

This isn't a daily driver and highway miles would be scarce but I don't want to rule out the possibility of jumping on the eastern freeway or doing a rural road trip...