[Boatanchors] MOV Choice for 120 VAC and 230 VAC

[LEE BAHR]

Is it wise to install a modern MOV across the primary of a boatanchor's 
power transformer input coil?  If so, which ones should I buy at Mouser out 
of the zillion of them for sale there.  (I'd be interested in both those 
used on 120 volts AC well as 230 volts AC).

I can't figure out which to buy.  Thanks for any input.  (I need to place an 
order at Mouser for some other stuff and will ad MOVs at the same time).

Lee, w0vt