So my 1978 280Z 5spd Manual normally drives and shifts pretty good. Today I was driving for a while no problems and later in the day shifting was getting difficult. All of the gears were hard to shift into as in I had to use force (no grinding occurred). But going into 1st was harder than the others and did have a little grind. Also my reverse has been kinda bad for a while as in sometimes it grinds if I try to shift to it after atart up. I already tried topping off the fluids which they looked fine anyways. Any ideas on what it could be or what to try?

The first place to look at is a dragging clutch.

Could be the master and or slave bleeding out. If you pump the pedal a few times does it improve? If you hold the pedal down does it get worse?