Did Colt ever manufacture a Large Pin A3 receiver that would fir my SP1 lower? Any info would be appreciated.

Daniel defense makes one, but it looks to be a pretty penny...

http://www.danieldefense.com/

Colt made a few of them on the preban Sporter Competition rifles, but soon switched to small pin.  They are pretty rare, usually sell around $400 or so.

(edited for model name)

Match Targets are all postban.  You are thinking of the Colt [b]Sporter[/b] Competition HBAR. Which is a preban flat top 20" 1:9 HBAR.

Yes.  The 6700, which I think as mentioned was a match target rifle.  I used one to have MSTN make me a large push pin M4gery for my large pin 6520 lower.  Bonus:  they were Colt gray so it matched my lower's gray (not perfect, but close).

Check it out!
[img]http://photos.ar15.com/ImageGallery/Attachments/DownloadAttach.asp?iImageUnq=15631[/img]
[img]http://photos.ar15.com/ImageGallery/Attachments/DownloadAttach.asp?iImageUnq=15632[/img]

BTW, the Daniel Defense large holes are Les Baer lowers that have been drilled out for large pin and may require minor fitting (which isn't a really bad thing)