the higher ratio rocker will increase lift a tad bit.
and in all honesty, i doubt you will notice any differences b/w the two. in my expiereces, ive swapped them, ran both ratios on my stuff and i never felt any real difference.
since the TFS heads are stud mount, rocker adjustments are way easier, so if you want some more lift, and are buying the rockers anways, might as well get 1.7s if you want. if it doesnt cause you any problems. your going to be buying pushrods to center your rocker tip on the the valve anyways. so it doesnt matter what rocker you run. 1.7s might cause PTV issues. you usually gain .030-.040 at max lift depending on the cam's lift starting out. so the gain at lower lift values arent near .030. the low lift during valve overlap is where your piston is most likely to touch the valves. just check clearance like everyone should and make sure all is good. but the TFS state one has some pretty high lift anyways so 1.6s would work just fine also.
when messing with stock style pedestal mount heads, i suggest leaving stock or 1.6s on, putting the higher ratio rockers on stock bolt down style setups throws the rocker geometry off. and the pedestal style setup is alot harder and more a of PITA to adjust properly. they arent just "bolt down and go" like the old myth floating around.