Hi Adam,
I read your post carefully, but do have some serious misgivings with your statements, I have had a couple of 741's and have read up on them, and have all the original manuals and parts lists, and have upgraded to a 1942 Mod 640 recently.
A 741 was designed as a 600cc - 37 cu in, (basicly a Scout, not a Sport Scout, that Military version was the 640) but the British and the other allies didn't want a 600, they wanted a 500cc for road tax reasons, That's when Indian took their new cylinders and drilled them for 2-1/2" pistons instead of the original 2-3/4".
There is so incredably lots and lots of misinformation about these models, it's not funny anymore, all the books written in the 70's and 80's had it all wrong, and are being quoted all the time!
So time to set it all straight, although it will take decades to do so!
My source here is a chief judge on Indians in the US AMCA, who owns every type of military Indian (exept the model 144 and 148, if there is interest for this I can post some pictures)
Re. the tyre pattern, there are perfect Firestone tyres now, that are an exact copy of the originals, and made in the US, a bit more expensive, but sooooo much better then the Chen Sings, email me for details.
Ron, I still regret selling that nice rear mudguard that's on your hybrid now!
Cheers,
Lex Schmidt