My Specialized Expedition came with a Wolber 58 40 spoke rim.
MA 40 were collectors Items + got More so When Mr Bontrager Scoured the dumpster at Specialized
and cut the 40 hole down and rolled them down to 559..
I would find the identical rim (mavic MA 40 36hole)
seek them on Ebay
have the wheel be rebuilt with the campy cassette (5-speed)
Its A Freewheel You should Know.. Regina not Campag but they both are Dead products
(Campag made aluminum cog 6 speed Race day freewheels .. Really rare at auction by now)
and the Regina Company is long dead
You just want A freewheel to use the Bike,. they will be coming from Asia.
The Hub can be cleaned and re greased with Fresh Balls , throw the freewheel away once you Get it OFF.
Going to 7 from 5 means spreading the frame from 120 to 135 (126 would do, but the current road standard is 130 or 135)
[turn the job over to someone who has done that before )You are needing a new chain by now
7 speed is 1980's, the pushing of more went to 8 (7 speed like Spacing)
then 9.10. & 11 packed into the width of 8..
./.