If buying today, I would get a new G2 Contender over a used G1.
I would also recommend getting 14" barrels.
First one would be a 22 LR.
Second a 223 Rem.
Third would be a 30-30 AI or you could go with a custom barrel in 300 Savage to put your brass to use. As was said above, the 300 Savage is borderline on being more that a Contender can stand pressure wise. Read up on the 300 Savage in a Contender, and tone the loads down.

That will take care of Rimfire Plinking/Practice, Varmint or centerfire practice, and a good all around hunting barrel for deer, etc.

Barrel Number 4 would be a 357 Maximum now that you can get brass from Starline. This is one of my favorite barrels.

Next I would get one of Tonys Forends on order in a 10" with a forward Bipod Stud. I have Walnut on my Contender with the old original Walnut with rubber down the back grip. The wifes still has the Rubber Pachmayer grip, and a charcoal laminate forend to best match it.

Back in the 1990's when I bought my original barrels I put Burris 2.5-7 scopes on them. If buying today I would still go Burris and get the 2-7 Plex. With the Burris the eye relief gets a little shorter as you crank up the power. Some do not like this. Myself I tend to hunt on 2-3X, and when working off a bench on 7X I am normally choked up tighter on the scope, so the change in eye relief is not a problem for me. I also prefer the 27 feet field of view at 100 yards on 2X with the Burris over several other pistol scopes that have 10-14 feet field of view on 2X.

I field carry the Contender in a Boyt Harness canvas case with Dee's attached to the loop handle close to the case body on the inside(4 each). I attach a strap to the Dee's and carry it with the strap cross chest with the case under my arm like a possibles bag.

Get a small and larger Brick shaped bag filled with something like airsoft pellets for under the butt, and a short Harris Bipod, and you should be in business.

One last thing, I would probably get all my barrels from someone like MGM, or Bullberry if buying new barrels.

Bob