I sort of stumbled on this approach, but I think its the best.
1. Get an Essential Arms pre-ban lower. If stripped, get the parts kit to make it a complete lower. Buiding your own may seem intimidating at first, but its really quite easy. The EA lower should run you $600-700, and they are excellent quality, and GUARANTEED to be PRE-BAN as EA didn't sell any stripped lowers, and they went out of business prior to 1994.
2. Put a pre-ban telestock on it.
3. Get a pre-ban M4gery upper complete. A complete upper is one that can be readily installed on your lower, with a bolt / carrier, that requires no assembly. By M4gery I mean a non-Colt. Preban uppers cost the same as postban uppers, so WHY NOT get the bayo lug and flash hider??? Bushy makes a good one. IMO, Olympic Arms makes a good one, but for some reason people don't like Oly, which maybe due alot more to Oly attitude than Oly quality.
4. (Optional) Put a two stage trigger on it. It'll cost you another $150, but worth it, if hitting your target is at all important to you.
All together you'll spend maybe $1,200 - 1,400. IMO the Colts ain't worth it. Unless you are gonna buy it to keep it safely stored away, and never shoot it, hoping someday before you die you'll be able to sell it at an appreciable capital gain. But I buy rifles to shoot.