I think the Hughes rocker setup will serve you well.
I have an early set of BB 1.7's that has and will make 950+ hp with a 4150 1050AN, Jones street roller and a 175 shot @511".
Our recently completed 511" had steel Comp Magnum rocker setup and they definitely would benefit from longer than stock valves when it comes to geometry. Comp rates them up to 850lbs which is more than adequate for most people, the only drawback to the Comp stuff is lack of rocker ratio options.
Skip the 1.6 stuff and give us 1.7's if anybody is listening.
If I were going beyond the 850lbs mark I'd be calling Jesel. Sonce I can't afford that I perused the classifieds until I found a used, rebuilt paired shaft rocker setup. My 2c on the current rocker offerings.
If it was me I would call B3 for a spacer kit and be done with it. ATI is to dampers B3 is to correcting messed up geometry on shaft rocker systems.