Apples and cinderblocks.

1st-gens use strut inserts, you remove the strut/knuckle assembly, unthread the top, remove the strut innards and insert a cartridge. The factory struts are "wet", you could actually mess with the valving and change the oil t oa different viscosity fairly easily. I used to just replace the original oil with ATF and call it good enough.

It's the same setup 240Z and AE86 and a bazillion other Japanese cars designed in the 60s-70s had.

 

That would be, and to the op the bilstein fromt strur inserts would be best if you want adjustability.

 

So, has anyone looked at these yet for the fb's? Paradise Racing Coilover Kits for Mazda RX7 RX3 RX4 R100 - Paradise Racing

 

Looks similar to the Techno toy tuning and ground control kits

 

What spring rate should I get on the front and what rate for the rear? Daily driver. Occasional spirited driving.

 

Stock rates are something like 100ish front and rear.

If you are lowering it, 170-200lb in the front is nice, 80-100 in the rear is nice. If you are keeping the Watts link, do not lower the rear very much at all. If it is on stock springs, it's probably already too low for decent handling. Due to how high the Watts is placed on the axle relative to the chassis' center of gravity, roll stiffness starts to go up exponentially as you go lower, which is why you want softer rear springs if you go lower.

Road racers will go stiffer in the rear, but they are also going WAY stiffer in the front, plus large front sway bars. It's all a balance.

I have 175lb springs in the back and a Watts, but it is a little higher than stock (STOCK, not 30 year old springs that have sagged an inch which is too low already), and it is also extremely sketchy on pavement at anything over 5-6/10ths. You can feel the inside rear tire start to come off the ground. It's great on dirt because applying power settles the chassis, but you can't do that on the street.