Hi Dave,
The stock bushes allow the suspension to move about and lose its geometry under cornering. Many of them are hollow. Before polybushes became available the only option was solid hardened bushes which required a hydraulic press to fit.
I found that polybushes sharpened up the handling and especially the steering response helped by uprating the subframe bushes as well. As you say there's lots of them The original bushes aren't noted for a long life so it's win / win in replacing them with polybush.
Polybushes on their own won't make the ride harsh. I found 200lb springs all round make for a firm and comfortable ride but that might not suit everyone. I'd recommend uprated shox as well as it stops the 7 from wallowing. If adjustable, start them on a low setting and firm them up until you find your preferred set up. I did it the other way round and almost shook my filling out.
I'd definitely fit the anti dive kit on the front anti roll bar (swaybar)as well. 7's have a tendency to stand on their nose under hard braking. It's cheap as it's basically a pair of aluminium blocks and longer bolts.
That's my opinion, so over to the others on here.
P.S. Rimmers aren't the only suppliers over here, try Robsport and S&S for prices here in the UK. The weak GBP should help you. Alternatively there are US suppliers that many of the stateside guys use.
Adam
TR7 V8 DHC Jaguar Solent Blue. 9.35cr Range Rover V8, Holley 390cfm, JWR Dual Port, 214 Cam, Lumention, Tubular Manifolds, S/S Single Pipe Exh, 3.08 Rear, 200lb Spax & PolyBushes all round, Anti- Dive, Strut-Top Roller Bearings, Capri Vented Discs & Calipers, Braided Hoses, 4 Speed Rear Cylinders, Uprated Master Cylinder & Servo, AT 5 Spokes and Cruise Lights, S/S Heater Pipes, Replacement Fuel Tank. No Door Stickers. Mine since July 1986, V8 from 1991