Bates knee Blocks - mix and match?

I found a cheap used Bates Isabel that I want to buy for my young horses. It doesn’t come with the Velcro knee blocks. I wonder if anyone has tried different styles on the Isabel instead of the normal dressage block? For example the AP or jump block ? Or a different brand?
I ask because I have long thighs and usually ride in a saddle with a short block (Custom Wolfgang Solo).

I have put different styles on another dressage saddle with space for Velcro blocks. Works fine for me.

I once put smallish Wintec blocks on a Schleese. Worked just fine.