If we can be reasonably certain that Larwood bowled around the 140 kph mark and was seriously quick, then why not look for eye-witness comparisons between pre-WW1 Test bowlers and Larwood?
Ernie Jones Acclaimed the Fastest —Australians have faced greater men than Larwood and Voce without flinching. 'Squealing was discountenanced in pre-war days — Australia favored for the Ashes. ...
trove.nla.gov.au
Bob Crockett umpired from 1901 to 1925 and was indeed a ‘World famous’ umpire when the newspaper article was published in 1932. He umpired in 32 Test matches, an Australian record which lasted until Tony Crafter beat the record in 1992.
So if the umpire says that Ernie Jones was faster than Harold Larwood then you have to take him reasonably seriously as he would have witnessed Ernie Jones up-close. Personally, I think that Crockett was being rather parochial in his estimation, but I don’t think that there could have been too much difference in pace between the two fast bowlers.
And so, if pre-WW1 batsman were able to score runs off a good fast bowler who (perhaps) bowled consistently in the 130s on uncovered pitches then we can assume that their techniques must have been pretty solid.
In my opinion, quality cricket of a high technical standard has been played for about 12 decades at the Test level. Obviously, quality batting, bowling and fielding is far more common at the lower levels in modern cricket; but the elite cricketers of Crockett’s time were truly elite.