King rear leaf springs for mk1 escort

I'm looking into replacing the 5 leaf van springs in my mk1 to a new set of king springs, it is a street car but may see the track in the near future. They will have to be modified to fit as mk1 leafs are 50mm and the kings are 60mm. Should I modify them for extra rebound leaf as well or just install them as supplied?

Ok cool, should I install them as they come or get an extra rebound leaf added

So if you have a 1975 mk1 shell what would you order? could you get the mk2 springs and they fit with no mods?

Took some measurements of front spring mounts and they are 65mm ID. Wilkinsons suspension have advised me to not machine bush down as there will not be enough material to fit and withstand sideways pressure for diff movement. They grind down the front eye of the spring to 50mm and modify bushes and crush tube to fit. They have apparently done it many times before.

Kizzy

Took some measurements of front spring mounts and they are 65mm ID. Wilkinsons suspension have advised me to not machine bush down as there will not be enough material to fit and withstand sideways pressure for diff movement. They grind down the front eye of the spring to 50mm and modify bushes and crush tube to fit. They have apparently done it many times before.

 
Mine and at least 3 others I have done all run the wider springs with a modded front bush.  I looked at grinding the spring down, however IMO modifying spring steel is a no no, and creates a possible problem area for strength.  The statement about there not being enough material for sideways movement is complete crap, even with the modded bush there is plenty.
 
Woz

So you reckon only having 2.5mm of bush shoulder is sufficient for each side? That I am definitely not comfortable with. Maybe my spring mounts are narrower than usual. Anyways I trust wilkinsons as they are heavily involved with racing and drifting and have been around for ages. Other research I have done has others race cars grinding the spring down with no problems. Thanks for the advice though

Kizzy

So you reckon only having 2.5mm of bush shoulder is sufficient for each side? That I am definitely not comfortable with. Maybe my spring mounts are narrower than usual. Anyways I trust wilkinsons as they are heavily involved with racing and drifting and have been around for ages. Other research I have done has others race cars grinding the spring down with no problems. Thanks for the advice though

 
Can't remember the exact thickness, but yes, absolutely comfortable with the mod, my car has been like it for 15 years, plus the others I have done, all race cars 0 failure.  Furthermore with the superpro bushes that I use the material starts to taper off on the bush anyway in its std form anyway, and when they are modified to suit all that is removed is the area past the taper. It makes no difference to the support of the spring whatsoever, in fact there is actually more contact area in the chassis AFTER the mod.
 
Anyone that knows anything about spring steel knows its not wise to machine it after it has been tempered.  If the area was made narrower during manufacture it would be fine, but you're talking about milling or machining it afterward, and that doesn't sit well with me at all, in fact IMO its stupid.  I would bet my lefty that machining the bushes is far safer than machining the spring.  Need I ask you which is worse if it happen to fail?
 
Woz