Bulkhead bypass vs ammeter bypass

I tried the link to the slant six site on wiring a shunt but it didn’t work. A shunt seems like a viable alternative as long as you use the correct resistor in parallel with the meter. It would be nice to see how it was done. I’ve got two cars with ammeters and I’d like to keep them. They are nice if you understand what they are telling you, and if they are working correctly.