Researching early VA guns would be your first step. That should answer your question about what type of furniture to go with. That barrel has to go further down, with pre-carves this is typical, so fully bedding the barrel will be the first task. You will want to know where your breech plug ends too because you have to plan for the touch hole which should go in front of the plug face. With the barrel down (and possibly back a bit) and your touch hole location known you can proceed with the lock, triggers, etc. Everything on a long rifle keys off that touch hole location.
Once you're got that far just keep at it. Sounds like a fun project.
dave