I have an engine stand just like yours with the wide, double front legs and I have never had issue with tipping like the style which has one single leg up front. Those will tip over with the head on. They tip on about a 45 degree angle half way sideways if you will. This commonly occurs when you try to roll the stand over a crack in the floor.
It is important to do what HRL suggests about how to attach the plate to the block, especially for an engine with the the head on. That head is stupid heavy.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission