I don't know how "average" I am in the 3RO world, but I have changed several sets of 2RO wheel sets for 3RO wheel sets. I have made Walthers - and others' - trucks into 3RO units. I have done 6-wheel and 4-wheel. The wheel sets (Lionel, MTH, Weaver, etc) I find on eBay, typically. I have been pleased with the results in almost every case.
Now, bear in mind, speaking of cases, that this is a "case by case" bit of business. Pointed axles have been no issue - in fact, more a good thing than a bad. The width of hi-rail wheels is greater than the typical 2RO wheel, and varies with brand, so some truck frame rubbing can happen. If it is slight, I ignore it - it will also wear in, with time. It does not always happen.
Try a set; get some wheels. Get a feel for it. Lots of variations and variables, but the beautiful (and otherwise) old 2RO stuff can be a gold mine for a 3RO Hi-railer who likes to roll his own, sometimes. Often cost-effective, too.
You will seldom get modern. ultra free-rolling Delrin-bearing performance with these upgrades, but most are not bad, and none have been worse than good Lionel Post War trucks.
