It's interesting that he was so much faster in Australia than he was at home. Here in England, he was about Malcolm Marshall's pace - my source for the comparison being a contemporary of Larwood's who reckoned himself to be about the same pace as Gus Fraser (and that that was considered to be quite nippy in his day). People on the 32-33 tour reckoned Larwood bowled considerably faster on that tour than he did at home as well, by the way.
I notice that you assert that today's conditions are very similar to those of the 1930s, an era in which Larwood did not manage to take 40 wickets in six Tests, nor take seven wickets for 12 runs in an innings. To suggest, though, that we shouldn't compare Larwood with Harmison seems a little harsh on Larwood, who did have a pretty reasonable record after all.
Oh, all right, I won't compare Harmison with Larwood. I'll just carry on with the comparison with Glenn McGrath.
For those who weren't paying attention before the WI series, I pointed out that the comparison stood at
M W Ave SR
GM 12 40 30.50 67.13
SH 12 41 29.63 63.87
Now let's see what happens five matches later:
GM 17 64 28.68 60.97
SH 17 72 24.43 51.36
Of course, you wouldn't want to compare Larwood woth McGrath, would you, becaus obviously Larwood is so much better that anyone making such a comparison would either be ignorant or need to see a psychiatrist.
Cheers,
Mike