Ian,
That was a very good price for such a nice condition .30-06 M1917. The .30-06 ones in such condition usually go for a minimum of $850 if and when they come up for sale.
I don't know if you know this but your rifle was one of the very last M1917's made after the war ended and before the contract was cancelled and all these ones made after the wars end went straight into long term storage. That is why the late date ones are often the ones in best shape as they were issuing and using them right up until Nov. 11 1918. The last official government listed serial number of these Eddystone made M1917 rifles was serial # 1,354,701 as of Jan 1919. The last officially listed Nov 1918 serial number was 1,181,908, so your one was completed sometime in Dec 1918 or Jan 1919 using a barrel made in Nov 1918.
Your rifle at serial number 1,319,102 puts it into one of the last post war batches of these rifles and the only thing that goes against it was these are the ones that were pumped out as quick as possible before they cancelled the contract as of Jan 1919. They were told by the US defence dept. that as of Jan 1919 no more rifles would be accepted and as the workers were being paid per rifle completed and sold they rushed to make as many as possible before the cutoff date.
These late production M1917's and especially the Eddystone ones are the ones with poorer quality parts and construction, especially the heat treatment as they really rushed the process and are the ones that often have the very hard micro cracked receivers when either re-barreled during WW2 or later or if they were dropped onto hard surfaces.
Although, if you use it as is it should be fine and should still shoot very well and safely, as these rifles are way over engineered for their intended later .30-06 use. Just don't drop the barreled action onto a concrete floor if you have it apart from the stock for cleaning, otherwise the stock wood will protect the assembled rifle somewhat brittle action if is one of the over heat treated ones.
BTW, your 1919 Lithgow SMLE that you got at the same time has a replacement barrel off a 1918 British Enfield made SMLE rifle but has a early Australian property mark (arrow inside a large D) and the rear sight looks to be from the original Enfield made rifle the barrel came off. Plus as you have already guessed to stock wood is not original.
