A good source of genuine USGI surplus 1911A1 parts would be golden, but they are getting scarce. A better solution is just to buy quality aftermarket parts that follows the GI spec and general configuration. I have yet to be dissatisfied with anything I've bought from Ed Brown.
I believe the spring/bar you are referring to is a 'full length guide rod' (FLGR). In my experience the only time they benefit reliability is when used in the Officer-length guns like the Colt Officer or A/O Pit Bull. The latter was cursed vehemently as an unreliable POS and A/O themselves will tell you that it was a mistake they won't be repeating. I have made them run however, following the basic procedure described in the linked article and with the addition of Brown's 'Reverse Plug' recoil spring system.
BTW if you're a 1911 newbie about the best 30 bucks you can spend is for a copy of
"The Colt .45 Automatic: A Shop Manual Volume 1" by Jerry Kuhnhausen. You'll soon have your terminology down and if you study it well from cover to cover, it will make you immune to much of the maelstrom of faulty information circulating about this fine old gun.