firstly Len, with all due respect, if its the bushes- wherever they are - that are faulty, replacing them with poly ones will cure and upgrade. why fit any non-standard part if that was the case, you surely would not advocate fitting a standard replacement part to cure then take it out again to upgrade with a better one

Matt, you need to decide if the main problem is the bounce or the wandering, they sound like two different things to me. then go for the shocks if its bounce and the bushes if its wandering.
get a second opinion from a garage, even if it costs you 1/2 hr labour, it may help your decision.
a final point with the suspension.. i have a sierra 4x4, with avo coil overs, full poly bushes, uprated roll bars. it is hard but only really harsh when you swap the 60 series tyres for 17" 40 series. but its fun....