If I had a Fryette and wanted to mod it and found out that Fortin could do it. I would rather sell my Fryette and buy a Fortin amp! Or let anyone else build me a custom amp that sounds exactly like I want. Sure if it's a very small mod, then I could do it but if it's a major one I don't see the reason for it and why would someone want a certain name on the amp when it sounds more like another brand? If it's a big modification that would most likely be the case.
If I modded amps myself I would certainly mod my Fryette and all my other amps I have