pike51 Just an observation, but you say you struggle to hit the hybrids, yet you are going to build these clubs basically at hybrid lengths. imo, the reason people struggle with hybrids is they are too short, much like the irons they replace. I know this was my problem. Then by experimenting, I found that building my hybrids longer than specs called for, helped a ton. Very easy to hit, with good direction. I've also started building my irons a lot longer also with same results, and much better scores.
The only problem I came across when going longer with the hybrids is that the lie angles are not very tolerant for longer lengths; I had to go through many different heads to find some that work well(Maltby STh2). Iron lies can always be adjusted, for the most part.
Carry on, good luck with the new project.