Turnsignals - if they are the black plastic, they should work. If they are the aluminum silver, I don't know.
I assume you are talking about just the turn signals, and not the stalks that they mount to.
The stalks from a R75 will not fit an R65.
The R65 has a front panel mounted to the upper and lower triple clamps that has mounts for the headlight, instruments, and turnsignals.
On the R75, the turnsignal stalks come out of a circle-mount that fits around the fork leg.
Throttle assembly - if it is from a R75, it is probably not set up for a master cylinder on the handlebar. Also, the gears on the throttle do wear over time/mileage. Something to consider.
The list of differences IS very large.