I was leaving things alone, because I didn't want to debate semantics, ie, when I said Stock Roller Chain...! The thread police are watching!
And for the matter, stock rockers cannot change its ratio, they don't magically increase lift, talk about myth! Roller Rockers provide less wear on the valve train due to less side loading on the valves, especially at higher lifts. The stock rockers are good, but if you want better, you go with Rollers, sorry! 1.65 is 1.65... 1.8 is 1.8, etc, and if you want too ensures ire to try it, it's not checked at the rocker, but at the valve. Do the clay method with 1.6's and 1.8's or 9's and swap a higher lift cam and do the clay again and tell me which has more "LIFT"... It's mechnical, it doesn't move, you don't get more from nothing. I've read this 100 times and it's BS. As a matter of fact, the higher ratio rockers do best by accentuating the cam lobe profile, ie, ramp rates are affected by ration, ie, quicker opening/closing on higher ratio rockers on par with its ration.
Double chain is the way to go, last time I can offer advise on this, it's a no brainer. Don't think too much, you're over thinking things! If it's the same $, go Double Roller.