I can't remember who it was who posted this on RFF but an effective way to interpret the light meter of the FT is as follows:
1/ Set your desired shutter speed
2/ Set lens to widest aperture
3/ Look at the meter and then close down as many stops as the number you read
Let's assume an f2 lens.
If at the selected SS the meter reads '0' then shoot at f2
If it reads '1', shoot at f2.8
If it reads '4', then stop down to f8
In following the method outlined I meter fully open, then count the aperture 'clicks' by feel and sound.
Although I've not tried it, if aperture priority is important for whatever reason I can not see why the same methodology can be applied to adjusting the SS or a combination of SS and aperture. Just a bit more mental arithmetic required.