Loyter,
Here are a couple swaps I have done and rough 0-60mph clockings before and after:
63 Nova, 3-on-the-tree, 3.08gear
Swapped 194-1v for 250-1v (NON-integral 250 head):
0-60 was about 13 sec, dropped to mid-10's.
Popped the clutch on the 250 and left 2 black streaks in my driveway. The 194 would never do this.
63 Nova, Powerglide 3.08gear
Swapped 194-1v for 292-1v (again non-integral head)
0-60 was about 16 sec, dropped to about 11 sec.
The bigger sixes really give those Chevy II's kick.
Since the 283-v8 was "banned from Nova production" in 63, I often wished that Chevy would have got clever and put a serious 230 or 292 into the 63 SS. It would have done quite well against Ford's 260-v8. But, hindsight is 20-20, sometimes...
Good luck with the swap, I agree with the other posts - use the head/manifolds/pan/pickup you have, just swap in the 250 block etc.
