That's about right for a stock 1971 and up transaxle; we always pretty much doubled the tach for the mph. It's terrible for a true Freeway Flyer unless your tire radius is considerably less than stock.
The engine, even a good stocker, will work well in that rev range, but air cooled engines need to have the rpm varied frequently during long drives, don't keep a constant speed and rpm for long periods.
A well built engine will rev freely past 7,000 and can live well at 6,000. We have an engined designed by AJ, with some of his parts and pieces installed, that takes 8,000 on nearly every shift and is running strong after three years.
Luck,
TC