[Vintage-race] Formula 4 spring rate question

[WSuman at aol.com]

I'm resurrecting a 60's Johnny Walker Formula 4 from a basket of  parts.  
Included springs are 150#, 250#, 310#, 350# and 480#.
 
Among other issues, I have spring questions.
 
I need to get some new springs (at least fronts) and am trying to make  an 
educated decision.  Weight is ~600#, distributed aft but I don't  know % yet.  
Motor currently is Honda CB-750, no ides what else may  have been in there. 
Sanctioned as 3/4 liter from virtually any  source.
 
Current front sets are 2.25" x 7.5" and I need to go shorter by  1-1.5" for 
clearances.  Rears are also 7.5" but bottom end is 2"  id. (threaded perch is 
pressed steel).
 
If anyone could direct me to a source of information on choosing spring  
rates, and a source for springs, I would be most appreciative.
 
Regards,
 
Walt Suman
Seattle
 
 
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