I am trying to use what came with the crane but also wanting to know in advance what will work and what won't.
That block may have come to you with the crane, but it didn't come from grove for that crane. Its likely off a old overhead crane from a shop/factory.
The weight needed on the block, is determined by how much cable is hanging on the back side of the boom. If you have 50' of boom out, there's 50' of cable on the back side of the boom. The weight of the block pulling down, must be more than the weight of the cable on the back side of the boom. If its not, when the block gets close to the tip of the boom, the weight of the cable on the back side of the boom- will overcome the weight of the block, and it will pull the block up into the tip sheaves.
So if you are running 9/16" cable, and have out 60' of boom. 9/16" cable is .59lbs/ft. 60'x.59=35.4lbs. So the block needs to be pulling down a effective weight of more than 35 lbs (with 60' of boom out). Only 1/4 of the weight in a 4 part is pulling down on the back side cable, so 200lbs of block or so- should be enough to hold it down.
Also remember when its cold, the sheaves don't turn real fast, and if you pop the lever into cable down real fast, its probably going to overrun the sheaves and make a mess of the cable stack on the winch. Slow is better in cold weather.
Time to look for another block.