Hello everyone - new to the forum from NC. My wife says I'm old  so I guess I am. If this has been covered elsewhere I apologize but I couldn't find it. I have a Colt that I bought new in the early 70's - model SP1, Ser # SP28***. This gun is practically new probably less than 100 rds through it. I've been thinking about using it for target shooting, etc and decided that I need to replace the upper so I can mount a scope on it. I've been looking at several from different manufacturers. Will these aftermarket uppers fit my old Colt lower or do I need to think about doing something else? Thanks in advance...

why.. I put a flat rail adapter on my A2's   works fine

look through this and pick your poison. you can mount a scope on your carry handle if you like. only draw back is it might be a little higher than it would be on a flat top AR. and watch some of the videos that are in the link to understand what we are saying.

https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=ar15%20carry%20handle%20rail%20mount