I don't think you've ever shot with a 450mm lens without stabilisation. Even with 1/1000 hand shake ruins most photos as even a slight tremor is massively exaggerate and it's frankly a stupid focal length to deal with unless you're taking landscape shots from the Moon. You need to double the shutter speed for every 100mm you extend to which becomes really hard except in the best light.
Like I said, there's a reason these lenses are in the bargain bin except for a handful of exceptions. The 35-105mm FD lens I mentioned is more than enough for most purposes. Otherwise I stick to modern zoom lenses even if they're cheap shit like the XC 50-230. Unlike primes, zooms significantly benefit from new tech