To check a coil you need a volt/ohm meter.
Naturally you need to find 12 volts going in at the terminal.
A coil is basically a transformer, 12 volts goes in and HIGH voltage comes out.
A typical resistance reading on the low (in side) will be quite low as there are not many turns of wire .
On the output side the reading will be high as there are many many turns of finer wire.
You read the high from ground (coil can) to distributor wire out, and the 12 vol from the screw terminal to ground.
To be sure of a good ground, scrape or sand a spot on the coil can.
I understand that the 650G is a Mazda engine and as such certain year ford rangers used that engine so auto parts carry replacements.
Good luck!