MkIII engine stamp number and Frame stamp number

I am a newbie with Norton Commandos, I want to buy an electric start MkIII Interstate.
I am purchasing literature to get educated.
Does the MkIII engine 325001 stamping
match the frame F125001 stamping?

Like 326123 and F126123?

Any photos of stamping please?

Can a seller purchase and stamp up and rivet a new frame tag as required to match?

How do you detect this new stamped frame plate, if so?

p400 said:

Does the MkIII engine 325001 stamping
match the frame F125001 stamping?

Like 326123 and F126123?

Click to expand...

Not until around May '75 and the 'F' was discontinued shortly afterwards (there seems to have been to have been a few 'odd' exceptions).

Note that the 'F' number (or later number matching the engine and gearbox) was stamped directly onto the frame headstock. The number stamped on the plate generally matched the engine and gearbox 6-digit number.

http://atlanticgreen.com/commandoframes.htm

p400 said:

Can a seller purchase and stamp up and rivet a new frame tag as required to match?

Click to expand...

Yes, blank certification plates (and the hammer-drive rivets) are available.

https://andover-norton.co.uk/en/shop-details/16740/certification-label-850mk3-usa-canada

p400 said:

How do you detect this new stamped frame plate, if so?

Click to expand...

If you are lucky, Andover Norton may be able to tell you which frame ('F1xxxx') number and plate number belong together.