Re: BIG tires on 1965 CHEVROLET??
Although not familiar with that exact model, I can offer some advice that I think would be on track.
#1: With stock axles I wouldnt recommend tires bigger than 35's.
#2: Although the old 6's are very strong, I wouldn't recommend trying to run it with oversized tires, etc. Especially if you want to do any serious 4 wheeling.
You didn't mention which tranny you have but that might be an important factor.
Perhaps others can inject some words of wisdom in here for you too.
All the best to ya!