Scopes are allowed in any match designated as "scopes only" or "AS--any sight".   For some matches (depending on organization) there may be restrictions on the type of scope.  Typically a match, class, or organization designated "traditional" means a early style scope (generally straight tube or relatively small diameter objective with outside adjustable mounts--some allow "clickable" mounts some require earlier style click less mounts) 
  In ASSRA matches "any scope" is literally that, sealed modern inside adjustable scopes or older outside adjust target scopes are permitted.  Our "traditional class" designation you are using outside adjust scopes of the early or "classic era---- winchester/lyman a-series scopes, Lyman Targetspots, Unertls, Feckers, Lischerts, etc.  
{the Quarter Bore side match requires early style scopes as best I recall. Their rules, as are the overall ASSRA rules, are posted here on the site}

Unless you are going to compete in an organization and/or matches with more restrictive rules you'll find that your 32-40 MB  outfitted with Lyman Targetspot or a Unertl, Fecker, Lischert target/varmint scope will pretty much fit right in with most of the rest of the rifles on the range. 

 Modern internal adjust target scopes work as well but they tend to be short eye relief and getting them mounted and positioned properly on a single shot action often requires special extended scope mounts.  
A good compromise, between the two, if you can find one is the long discontinued Redfield 3200's the long tube gives a more or less traditional appearance and good eye relief with out some of the mounting issues.

first step is to check the rules of the organization and the matches you are interested in participating in.

In a reproduction MVA's B 5 is as close as you are going to get. Exact copy of the Winchester scope.

Boats

Yes, getting any old scope worked on is a huge pain! I have a friend who does it, but wants to remain anonymous, as he's got more work than he wants already. He rebuilt and antiqued an old Tasco full length scope for me, plus a few ols Stevens and Lymans scopes. The full length Tasco is better optics than any old full length scope I've ever looked through! Plus much finer crosshair than the original heavy/crude crosshairs.
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Here is link to the MVA site with the Winchester B5 scopes - (You need to Login or Register to view media files and links)
Google is your friend.

long-scope envy ?????      VBG

just wondering,  say you had a given x power in differing lengths of those NVA scopes, maybe the Win/Lyman 5 and one of the full length tubes.    what would be the difference in them when looking through them?  brightness?  field of view? etc etc, assuming the only variable would be the overall length.

Notice no difference in brightness between the 23" & 28" MVA scopes. They are so bright that I use the MVA with its 6x power rather than a higher power STS or Unertl, which seem dim by comparison. Prefer the sharpness/clarity of the MVA. Personal preference.

Have not looked thru their B-5 model, which is available in 3x, 4x & 5x.