Can anyone tell me where I can find diamentions or specs on how to properly set up a side-car, I bought a sporty with a side-car on it rode it home and unbolted it, it was the biggest peice of shit I had ever riden. I still have the side-car and would like to put it on my 84 Shovel to take my kids out on the road but I would like it to handle !.

< 12 inches lead on the chair wheel, 2" lean out at top of chair, 2" toe in (like rail road tracks running into the distance, your chair wheel slightly runs toward the bike line......

use 4 point mounting system two up two down.....post pics.....i like sidecars

If the shovel has a wide glide front end you can get raked trees for them, that can help as well, providing everything else is set up right.

Chopaweeza is correct about the forks-the reason being not only reduced trail,but they have an anti dive feature-everything else is correct except in Victoria ,unless the forks are original equipment they require engineers cert.Same with the chair setup -engineers cert required if outfit isn't factory or bike didn't come with a chair option.The steering damper helps as shortening the trail makes steering easier -quicker but real twitchy.
I have an outfit with hagon shocks ,leading link,15' car tire,vw steering damper & its great-basically as discussed by Chopaweeza.
There are 2 schools of thought on front tires-side car type -square profile-long lasting -hard compound,limited tire size-or standard tire -stickier ,wider choice,not as long lasting ,but when cornering the bike does use a little of the rounded part of the tire-also now they have multi compound tires hard in the middle & stickier on the edges.
I have a couple of books on side car setup & will drag them out ,but I think the lead is only 4-6 inches ,not <12-but that would be dependent on wheelbase-the other measurements sound ok.
One thing that hasn't been mentioned is a massive brake up grade-not only have you got approx 100 +kg additional weight-like having a Large pillion on all the time-the brakes on the old shovel are marginal on there own.
If you can set it up- a sidecar wheel brake-either linked to back brake or separate pedal for cornering help-make a big difference.
Cromag is right about the linkages ,go 4 point not 3 as the old standard Harley & also sprung chair swing arm not rigid as per oem Harley-suspending the actual chair boat gives a little extra comfort-(check out Steib side cars they have a great system) to chair passenger & also a door on the chair helps getting in & out-but if u r ridding ,i guess that's not all that relevant to you-except helping u r passenger in & out of the chair