Seriously, this time. I would get a good sized piece of cardboard and using the parts you have, draw a mock-up of how you plan to put it together. Draw a line for the top of the barrel, place the barrel on it, draw a line along the bottom of the barrel, then mark the end of the 3/4 stock you plan. Mark the lock location, allowing for the breech plug length and drum/flash hole, then lock plate and trigger location according to sear location. Mark trigger pull length ( say 14-1/2 Inches) and drop at heel. Then draw in outline of stock. Allow for the ramrod hole and bottom of forestock. Now you can see if your parts will work together, and what you will likely end up with will fit you. Cut it out, put it up to your shoulder and see if you are looking down the top edge…….ie what would be the line of sight of the finished gun. Make changes if needed to fit.
Sounds like a lot of work , but it’s not hard to do, is educational, and cheaper than starting over because it doesn’t fit, or doesn’t look like what you want.
Been there.