Technical let me put me idea up here, before I forget - 35 36 rear bars in a 40 with a 59.25'' wide 8''

buy some 35-36 rear radius rods
leave them stock at the front
IF they use a 1/2'' bolt to affix to the original torque tube that is a 1/2'' thick tab
'simply' buy a leaf spring bush that is 2'' wide. 1/2'' bore
bolt the front of the two rasius rods to that with a 3'' bolt 1/2''
erm
the front is now 1.5 inches wider
when you mount the bars to the rear axle
mount them 3/4'' further outboard
spring drops a tad = bonus
make the front mount to receive the bush bolt in, so you can weld it and press the inner bush in.....
something like that