If I had to go back to 1965 and hunt with the technology then available, then like a number of others have indicated, the thing I'd miss would be modern hunting clothes. I well remember the days before they existed, when you'd have wool for cold weather, which would get damp and stay damp, and chafe. Cotton when it was hot, which would hold sweat against you and again you'd chafe. Rain gear was nylon - which ended up with you just as wet as if you didn't have it - or oilskin which weighed a ton - and both were noisy.
The other item I'd miss, though not as much, would be GPS. I learned to navigate with map and compass, and can still do it of course, but there's nothing like GPS for getting you home in the dark or socked-in with fog, or on flat and trackless desert, or for marking a deer you've dropped and going right back to get the rest of it.
Good rifles, good knives, decent optics and decent boots were all available by 1965, and while I have used laser range finders I personally feel no need for them. Camelbaks and LED torches are items I like but could live without too.
