I just got through swapping a 200 with a 3.03 manual 3-speed into a '62 Ranchero. See details here:
http://fordsix.com/forum/viewtopic.php?t=31268
I saw that ebay auction, and I hate to say it, but an earlier (pre-79 or 80) block may have been a better choice, because of two
possible issues:
1. Bellhousing - which I don't know about, by the above comments it may not be an issue. I do know that any bellhousing later than the dinky early (pre-66) will have the upper two bolts very close to the firewall. You can slide the engine forward on the mounts as long as the fan doesn't hit the radiator, or take a hammer to the firewall.
2. Low-mount starter - if the starter mounts to the block down low, it's likely to interfere with the steering center link - which can be fixed by swapping the centerlink from the top to the bottom of the draglink and pitman (?) arm. If it mounts up high just under where the exhaust manifold will go, there's no issue at all.
For other things you'll have to deal with, see my thread above. It's really a simple swap as far as the engine goes, the things that will need your attention center around the transmission. I stuck with a manual, but upgraded away from the itty-bitty 2.77 gearbox. What trans is in your '63?
As far as carbs go, I really like the Holley 5200 (aka Weber 32/36 DFAV). Probably have to do some rejetting, depending on where you get one from, but there's lots of info here on that.