Outstanding war story troop! Welcome home, thank you for your service to the republic and welcome aboard our M-14 community.
You could not possibly have done better when it comes to a commercial M-14 than what you just bought! I have three Polytech M-14's and an unfired preban Springfield Armoury M-1A built with USGI parts, that I bought brand new back before the ban in the Spring of 94.
Two of my Polytechs are heel stamped prebans imported by Kengs Atl Ga, with serial numbers of under 1,000. My last Poly is a brand new unfired IDE Mich, just like yours that I recently found for $975.00 OTD. I actually paid $250.00 cash and traded a Dan Wesson Pistol Pack .357revolver for mine. I was tickled with the deal since I had less than $125.00 in the Dan Wesson Pistol Pack and that was in a trade when I got it back in 1991. I'd never even fired the thing and had always considered it to be nothing but trade goods and that' how it turned out.
My two heel stamped Polytechs have been converted to USGI parts, TRW on the first one and USGI Springfield on the second. With my latest IDE I've changed the stock for a CMP USGI walnut stock, Springfield trigger group and Springfield rear sight. I've added a CMP OD green USGI reproduction sling that I picked up at CMP South to all three of them. I haven't gotten around to shooting the IDE but I will next Spring when the weather breaks.
For the record, the receiver on your Polytech has the correct dimensions and proper metalurgy, in other words it's built from comparable forged steel just like the USGI M-14 you latched onto during your tour in the sand box.
Their barrels are chrome lined and are equal in accuracy to the three real USGI M-14's that I got for my police department under the Feds 1033 program. The op rod is one piece forged, just as are the TRW op rods and they are built from good forged steel and they work great.
None of those three things, (receiver, barrel and op rod) need to replaced or concerned about. Everything else could stand some attention. The rear sight is crap, which you will find out.
The gas tube assembly and piston were not built from stainless steel like the USGI M-14's were, instead they were built from chrome molly. The factory gas tube assembly will work and work well but down the road you might find a USGI gas tube assembly and piston... But there's no rush on this one.
The trigger group can stand some improvement, the hammer and trigger are soft, as are their pins. so I'd change them at some point too and you will be ok with the trigger group.
We aren't talking about much money here and you don't have to do anything right now, except maybe replace that rear sight. Then shoot the crap out of your new M-14 and enjoy it.
By the way a USGI M-1 Garrand sight will fit and work perfectly on your M-14. But be aware the Garand rear sight is calibrated in yards and the M-14 in meters.
You've already said that you intend to replace the stock with USGI. If you do you will have to replace the connector and it's little retainer pin.
The connector is the part that holds the operating rod guide in place on the bottom of the receiver. This is a cheap modification but must be done if you change to a GI stock. If money is that tight, then you can just leave the Chinese connector in your rifle and fill the indent in the GI stock, adjacent to the connector with JB Weld and call it good to go. That's up to you.
Good luck with your new M-14 and enjoy it as it for now but ultimately when you are finished with your project, you would not trade your finished M14 rifle for anything that SAI is currently building. Your rifle will be built from forged parts while the Springfield M-1A's are built with commercial casting from Taiwan and they are having issues with them.
When you are done with the modifications, your rifle will make you proud of your decision to buy it and do it yourself. Because your rifle will shoot like a house on fire and be a thing of beauty and pride to you.
If you need help we will be glad to walk you thorough making your M14 into what it should be. If you'd had bought an M-1A for $1500.00 you would have had to do many of these same things to it and still had a rifle built from castings. After you've been here you a while you will learn these things for yourself.
http://www.raparts.com/Products/m14parts.html
7th