I would try your local farm supply, they likely have lighter edges more suited to your needs for tractor blades. Not sure now you have purchased it how much use the dozer portion of the excavator you'll need.......only you can answer that, trenching requires lots of use, digging ponds not as much.
Grader blades generally have the bolt holes offset for one usage, bulldozers are centered and can be flipped around, both are bolt on. I was fortunate enough to pick up some brand new grader cutting edges from the municipal district as they had previous new stock and switched grader brands and the new pattern didn't cross over........I'm building a 12' grader blade as a project but it's currently taking a haitus........LOL
AR400 is generally used for the plate and skins, the cutting edges are harder.
Opportunity knocks once, temptation leans on the doorbell.....