Print quality of grey text on rich black background

i've been working on various print materials require me use lot of grey text @ various shades set on black background. understanding can terrible due misregrestation of 4 colors. here's example of kind of text i'm working with:

 

 

this how have things set right now:

 

• rich black swatch: c70 m50 y30 k100
• all text uses same swatch @ various tints in indesign (15% tint headlines, 25% tint body text)
• body text size 8 pt/10.8 pt, headlines 14 pt

 

these being printed on offset press , printer isn't local, don't proofs. there better way set or best can hope for? help!

i wonder type of paper planning on using these pages?  total ink amount 250.  should concerned dot gain , ink spread.  oh, nice rich black on screen isn't nice on press number of reasons.  have thought using spot black? why use process if have black?  unless, ofcourse, have other elements use process colors.  have know press , paper before can make judgement effectiveness of rich black screen tinted variants.  bite bullet , let file fly.  or, use black screen tint variants lesson problems on press , readibility.  no proofs?  no press check either?

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