Hay ck: if you decide on a Para in 45, get yourself a 400 Cor-Bon barrel and I'll give you some of my data for indoor bullseye loads - I think you will be impressed with the accuracy of that 40 caliber barrel and how easily she shoots bullseye. If you want to take it up the ladder from there we can talk hunting or silhouette loads.
If you want to go with a 40 caliber, get a 357 Sig barrel for some medium bore fun.
If you buy a Para in 45, you may wish to check with the factory to see if they would sell you or fit a 40 caliber slide to your pistol so you could shoot 4 different calibers. Of course, if you find a 1911 in 9mm, you can go the 38 Super/9x23, 30 Luger or 7.62x25 Tokarev routes as well.
Gee man, a guy could have a lot of fun doing that. Mikey.