If you're planning to go with an M14 type, I would definitely shop around and buy or build up an LRB instead of a Springfield... unless you find an older Springfield that uses all USGI parts and barrel.
LRB's receivers are forged and truly "to spec" where SA and Armscorp are cast and not neccesarily to spec.
Newer SA's use a lot of non USGI cast parts and, as you have seen in several previous posts, there have been quality control issues. Newer SA's are just not worth the money, as far as I'm concerned. I'm not an "expert", but have owned several SA's plus one LRB. One SA serial numbered in the early 1980's range was a pretty nice rig, but the other's just flat sucked in comparison - op rods were soft (one would jump out of the track once in a while), and even high-dollar scope mounts didn't fit right. The "rack grade" LRB I built with a (Wilson chrome-lined) barreled action with headspaced USGI bolt I bought from LRB was a bit pricey after I finally scrounged up all the other USGI parts, but by far the best.
The only real advantage the M14 has over the FAL is that the sights are "rifleman's" sights on an M14, whereas the sights on an FAL seem to be almost an afterthought. In my opinion, an FAL carries better and is probably more rugged - less prone to needing to be tweaked to keep it running. But an FAL that weighs under 10 lbs with sling and 20rd mag and will shoot much under 3 MOA is rare, from what I've seen and heard from others. ALL of the m14/m1a's I've ever owned would do under 2 MOA with any decent factory or NATO surplus ammo I tried using iron sights.
But then again I doubt anybody could really outshoot a 2.5-3MOA FAL with mil-spec iron sights without a machine rest anyway. Which brings me to optics - my experience with optics on an FAL just flat sucks - tried the ARMS mount and the DSA, both of which were nowhere near 100% reliable... though I would cough up the cash for a DSA mount again, simply because there's no better option.
Putting optics on an M14 type is not a problem, as long as you stick with the "expensive" scope mounts like Smith, Sadlak, or the old style ARMS #58 (new #58's restrict your access to the ejection port too much in my opnion, and have been known to cause ejection problems due to brass hitting the underside of the mount).
There's LOTS of info/experience to be learned from over at www.m-14forums.com. Several builders that specialize in m14 builds that are not unreasonable in their prices if you're afraid to try to build it yourself - Warbird is one that I'd use. After it's barreled & headspaced it's actually very simple and easy to assemble - doesn't require any special tools etc. Also, older m1a's and LRB's can be found for sale.
When I built my LRB, they were selling "package deals" with barreled/headspaced receivers with GI bolts and GI trigger groups. You might check 'em out - www.lrbarms.com
Good luck!