"Stroke" of an engine is measured from Bottom Dead Center to Top Dead Center of any one cylinder.
In the old days the "extra" metal was welded to the back side of the connecting rod journals. This had to be done by a machine shop with a submerged arc wire feed welder. The flux is poured over the weld area as the crankshaft is rotated and the wire is fed into the weldment. Then the crank had to be allowed to cool down and checked for straightness. It is then put into a crank grinding machine and the new stroke is ground into the connecting rod journals. Then the main journals were "trued-up". But now you can just get on line and order any stroke crankshaft your pocket-book can afford.
Most of the time I think you will need to check to be sure the connecting rod lock nuts clear the pan bolt area and the camshaft too. I think there is a smaller diameter camshaft you can buy so the rods will clear for stroker engines. I think they are called small circle cams. They have the same lift and all that but are a little smaller in diameter.
To remove a freeze plug I use three tools. One is a big hammer. Then comes the flat nosed punch. And lastly is a pair of channel lock pliers. You might call them "water-pump" pliers.
I use the hammer and punch first. I hit the freese plug on one edge of the plug. This causes the plug to twist a little in it's opening. I then switch to the channel-locks. I "hook" the large jaw into the freese plug and then pry the plug out like it was a nail in a piece of wood. Works great.
There are two plugs on the chevy small block you want to be careful removing. They are very close to the cylinder and if you hit the plug too hard you can crack the cylinder. BTDT!
A small handful of engines with center-mounted spark plugs you can measure stroke by using a coat hanger or welding rod in a spark plug hole. Caddys and Hemis are definitely in that category. You simply stick a welding rod in the spark plug hole and measure the stroke.
Another way to increase stroke is to offset-grind the rod journals. It requires special rod bearings, but it can increase stroke a bit.
Curtis, that works with other type engines as well. Not quite as accurate, but usually very close, within 1/16". I know, 1/16" can make a few cubic inches difference! It works for verifying engine size (assuming you know what stroke it's supposed to be) reasonably well though.