Auto Parts-Used is the yellow pages section that should show you where the wrecking yards are in your area. Use online yellow pages, they are user friendly and provide you with driving directions.
Yes, not all small blocks are created equal/the same. If you have an older sbc built before 1986 it has a two piece main seal, early style intake manifold with 12 bolts instead of 8. Everyone has their favorite casting, mine is a 3970010 because I have yet to find one that was not a 10/20 block. That is a vintage block with 2 piece seal, most were 2 bolt mains with driver side diptstick location.
1986 got the one piece rear seal and 1987 added the different intake manifold bolt pattern and center bolt valve covers. Not all heads have 1.94 intake valves either, some have 1.71's and are very likely to be included with a 2bbl motor.
Remember that not all heads will have the accessory mounting holes you need so arm yourself with the info you need before you buy anything.
Search for past threads that show a link to block casting numbers which will give you an idea of what year vehicle to look for that has the features you need if picking out an engine at a wrecking yard. Wrecking yards by the way are probably the most expensive route to take if you want to build an engine. Scouring the want ads, ebay, etc. will get you what you want cheaper unless you have a good relationship with a yard operator.