The way I see it with the cost of the parts that you are looking at (around $510+shipping) and the cost of a new Para GI Expert in stainless ($600+shipping & transfer), that's over $1100, and that's before gunsmithing fees if you can't fit all of that stuff you want yourself. If you really absolutely must have a stainless gun then why don't you get a Springfield Loaded Stainless? It will come with an extended beavertail, ambi safety, a nice low mount adj target rear, good fitting and a match grade barrel. That will save you $140 in parts and a lot more on gunsmithing, if needed. All you'd need to add would be your magwell, front sight, grips and ignition parts (although a trigger job on the stock parts would be just fine). Also, it would be an understatement to say that there's a few folks out there shooting Springfield 1911s that do fairly well .
Springfield Loaded .45ACP MSRP is $1081 and you can find them online from ~$815.
So total cost for your Springfield Loaded if you can install parts for yourself:
Gun - $815
S&A Magwell - $80
Dawson FO Front Sight - $35
VZ Grips - ~$65+
Total without SVI Trigger - ~$1,000
(And if you don't want a trigger job on the stock parts)
Total with SVI Trigger - ~$1200
So at most you are spending ~$100 more than you would by building up a Para GI Expert but you are getting a well fit, forged, very reliable and proven firearm that is backed by one of the best customer service teams in the country. Of the few guns that I have had to send to Springfield, no arguments have been made and the issues have been corrected swiftly and successfully.