They're way before my time, too.  But the fact of the matter is that it's essentially the same thing.  If you can work on a small block, I guarantee you'll be alright with a Y Block.  Actually, I'd say if you can work on an engine, you'll be fine with a Y.
I don't know if anyone here can help with your header question, but I will give you some things to think about.
Unless you go with a fuel injected, roller cammed 302, you'll be way down on torque.  This means the car will be slower, less fun to drive, and get worse mileage - and you do a lot of work, or pay someone a good bit of money to do this.  That just doesn't make sense.
If you're going to go through the hassle of a swap, make it count.  I wouldn't consider anything smaller than a 351, but if I was forking out the dough or spending the time, I'd go big block, 390, 460, something like that.  If I'm going through all that, I want to notice it.
I don't know your skill level or circumstances but a swap will involve a lot more than may appear at first glance, money and/or time and/or skill.  Make sure it is something you can really take on so that it does not become another butchered, unfinished engine swap car for sale.
I really can't think of any reason to swap, other than for power.  If you need 600+ streetable hp, I can understand.  Otherwise, it just doesn't make sense; there's not a whole lot to gain.
Why are you considering a swap?          
			    				
			    
Lawrenceville, GA