Keep your Monroe seat. I have one on my '50 B and it is a lot more comfortable than the standard seat. Plus, Your B will look different from the other 99 that may come along. Mine was dealer installed when delivered to its original owner in 1950.
If your shock goes bad, NAPA has a replacement, Part # 2085. Cost $10.99 the last time I bought one.
Best of luck with your B.