First of all, check out this thread: CLICK HERE
Also look at this thread on spring repair: CLICK HERE
The seat in this instance was from a '53 Chevy and had sinuous wire springs, not coil springs, which would hold up better over time than the coil springs in your '41. Chances are that your seat is probably pretty solid on the passenger side, but is probably pretty weak on the driver's side. Over time, coil springs lose their temper and become soft and not very supportive. Re-padding the original seat on a '41 (or any car seat that still has cotton and latex rubber for padding in it) is a no brainer. You are probably going to have a real challenge finding an upholsterer who is knowledgeable enough about seat spring construction and the different types, densities, and qualities of foam to be able to re-do your seat exactly how you want it. Believe it or not, the seat cover itself is the simplest part of the whole package. It is usually not possible to just switch out coil springs and put in sinuous wire springs or some other kind of platform, the technology is different in each instance because the base of each seat is totally different. The only way to know if your seat is salvageable is to strip it down to the bare springs and see what you have. The old coils could be replaced, but be prepared for some sticker shock at the cost of doing a complete makeover on an old seat. The job would be extremely labor intensive along with the fact that new coils and the right kind of foam are not inexpensive.