I Have TWINS !!

Newbie here. I was looking for a nice daily driver without a fuel pump in the tank and with a carb on the engine. I found a 1984 Olds Delta 88 with 34698 miles. Original owner, never seen salt. Here in upstate NY, things get rusty fast! Well, I could not drive it in the winter so I found another one to use in the winter with a Rod KNOCK. It already had a turbo 350 installed and a Holley carb on an Edelbrock manifold and a vacuum advance HEI distributor. Out came the 307 Olds and I did a complete rebuild. Runs well and drives real nice but is a little slow with 2.41 gears. Thinking about putting a Small Block CHEVY in the nice one and an 8.5 rear. Could you guys make a suggestion on which rear axles are the easiest ones to find? THANKS
JIM