Interchangeable sink tip length for streamers

[flyfysher]

I got a couple of Galloup streamer videos and I decided I'll focus on going after larger trout with streamers this coming season.

By way of background, I plan to fish my pretty much unused 8 weight Rio Versi-tip (not the Versi-tip II or Scandi versions) fly line for this purpose. The vitals are: running line = 62', back taper = 4' and floating belly = 18 and 1/2'. It has a welded loop for attaching interchangeable sink tips.

I was told by the guy at the fly shop to disregard the 'type' and instead focus on the sink rate or ips (inches per second). That makes sense to me assuming there's no industry standard as to what the 'type' is.

Further, I don't usually cast that far when I'm out and about. I usually keep it 40' and under if not at 30' or less. So the point here is to be able to turn over the fly quickly and not suffer too much casting fatigue. I intend to throw large, generally unweighted streamers.

I've the following sink tips with loop to loop connections:

15' floating/9' sinking (overall 24') - 5.5 ips sinking tip;

24' - 5.5 ips sinking tip (don't ask why I've multiple 5.5 ips sinking tips. It's a long story. But I've no problem with cutting this tip down);

15' - 7.3 ips sinking tip (I actually have two of these as well. Again, it's a long story to explain); and

15' - 8.4 ips sinking tip (I only have one tip).

So, the question is this. What is the ideal length, if any, for the sinking tip in terms of cutting them back?

I'm thinking my primary go to tips should be the 15' - 7.3 and 8.4 ips sink tips.

I plan to use the line on my Sage 9'-6" VT2 8 weight rod and I'll be primarily fishing the rig on the Colorado (CO), the Green (UT) and the North Platte (WY). I'll probably have an 12" section of 20 lb. butt and 8-10" section of 15 lb. leader.

I'm thinking the ideal sink tip length would be 7' to 10' but I just don't know. Any advice?