If you were just going to use the home made bbl vise to remove and reassemble revolver bbls, I don't see any need to make the base and the top plate of anything thicker than 1/2" for the the simplest of vise designs.
If you are going to make the type where the bbl blocks (oak, lead, whatever) are 1/2 round on the outer surface and the vise upper and lower plate are cut out for that semi circle configuration, of course you'll need much thicker material to surround that feature.
But I never needed that style for removing just revolver bbls or things like 22 rifle bbls from Win & Rem pump guns and semi autos.

The biggest thing is just making sure nothing slips and turns when trying to remove or tighten up the bbl. Horizontal, verticle use,,type of jaw(s) style, type of wrench, ect ,,as long as they are all secured firmly so they don't mar the gun part and the parts don't slip during the process.

It helps being able to see clearly the junction of the bbl & frame or over the top accross the sights so when reassembly comes around you can reallaign to an original witness mark that you can easily see or square up the bbl to the frame by use of the sights or sight dovetails and action flats.
The latter often leaves you going back for a little tweek to get it just right. Eyeballing the assembly that says it's straight up with a square and level many times won't look correct once you have it out of the vise and in hand. Like houses and used car salesman, most things about them aren't perfectly straight.