Nice write up and the caliper externals look really good for being 20 years old, or is that fresh paint?...suggest a grease gun (which I have several for different purposes). Come to find out, the bleeder valve is just like a grease zerk in size and it will clamp on (I had to unscrew the gun tip apart to get it to release however). That gave me a good slow controlled push of the pistons. It also required a few C-clamps to control them so one didn't push out and loose all leverage. Unfortunately I wasn't thinking and didn't take any pictures.
Cleaning up the gun grease was not fun but wasn't hard. I soaked it in a bath of Simple Green which I like to clean parts, then a little brake cleaner and compressed air to get it ready for seals. Before I did seals there was internal corrosion so I ran a wheel cylinder hone in it and also used a pick tool to clean the seal grooves.
I've shot pistons around the garage using air before, but those probably weren't all that stuck. The grease gun is a great idea that I hope I never need to remember......
I noticed your Harbor Freight magnetic parts bowl which I bet many of us have in our collection. So, the question is how many does a person have and how many did said person actually pay for and not get as freebies back in the day Harbor Freight used to give stuff away all the time.