Rear subframe bushes should have little or no effect on the front end

The subframe donuts were replaced about 18 months ago, one was ok ish, tother was almost in two pieces

So no wonder really that the handling was so hideous before

My 234k car currently consists of:
Front: stock original rollbar bushes, new pattern trackrod ends/balljoints/droplinks, recent GM rear bushes, front poly bushes, stock GM plod shocks(renewed 90k ago), pattern top mounts (again 90k old), original plod springs.
Rear: stock original rollbar/trailing arm bushes/diffmounts, stock GM self levelling L4 shocks (renewed 110k ago), original plod springs, Pedders poly subframe bushes. Awaiting shock top mount kit from AndyC, as top mounts have collapsed slightly.
The only two developments that remain to be tried with the stock suspension are to polybush the front lower arm rear bush, and to replace the front strut top mount with a heavy duty Pedders one from the Monaro.
The improvement of the rear end is, I believe, more than simply replacing a worn out bush, as there is minimal give in the poly compared to the stock bush.
My aim is to firm up the factory suspension, (plod springs seem to be unbreakable), with a view to improving chassis control and eliminating the weaknesses of the standard bushes. The only point of contention is the front lower arm rear bush...
In answer to the cost, £108 including next day postage