Is 85 mph your club head or ball speed with the 7 iron? The HZDOUS Red is a high launch shaft, as well as the Kuro Kage shafts.
If that is ball speed, the R shaft should work. If your club head speed in driver is under 95. Unless your transition is overly quick, it shouldn’t feel whippy or have a wide dispersion.
If your club head speed for the 7 iron is actually 85, see a fitter.

85mph is the 7 iron clubhead speed. I should have mentioned that, and I realize a fitter is the best option.

Think that is a question you should be addressing with the fitter that set up you up with the rest of your equipment. The obvious is always the right answer. With respect. =)

I have senior shafts in everything from the Driver to the Wedges.

I think 85mph with a 7iron is right on the line between Regular flex and Stiff flex. So your iron swing characteristics probably play a bigger factor than just swing speed (like with a driver).
If you like to swing smooth/easy = regular flex probably allows you to release the clubhead with better rhythm and timing.
If you like to swing hard/fast/quick = stiff flex probably allows you to control the clubhead for better dispersion.

Most of the time, regular flex is lighter in weight than stiff, so if overall strength (including later holes in a round of golf) is a concern, then regular flex may be a better iron choice.

To your question on driver shaft: you're probably swinging driver mid-high 90mph, if so I would stick with Stiff. Meaning a different driver flex than iron flex.
Given the Evenflow T1100 is a low launch, low spin shaft and the Hrzdus Red is a mid launching mid spin shaft, you'll probably achieve a higher ball flight with a change. You could also consider a higher lofted clubhead if you are switching from your current TS2. And the clubheads are adjustable for more loft.

Good luck on your journey!

Thanks James. That was very reassuring. I went with a TSi2 11 degree head with a stiff flex HZRDUS Red 50 shaft.

Go to the fitter and ask them, im sure he would help :)

That's a hard one to answer for anybody on this site. Even if you can't get to a fitter I would try to find one you can talk to about it. The shaft has far more influence on your swing than the clubhead, and swing speed is only one of about half a dozen things to look at when selecting a shaft.

I have had similar questions during my recent fittings. Surprisingly, to me anyway and to at least one Titleist fitter, my irons are Stiff, but my Driver, fairways, and hybrids are Regular. I find the stiff shafts in my irons give me better control and dispersion than the regular shafts.

I’m borderline R-S. I get more control with stiff. I can generate 95mph but usually swing 85. The best thing I did over a year ago was switch my driver shaft to Diamana 62 x5ct S.

My problem with a regular shaft is if I get “anxious” I’ll pull it.

I actually get better distance with stiff on the fairways and hybrids. I’ve been using stiff on my irons for 4 years now. I’ve simplified my irons to a strong 7 (32) and a weak 8 (39). I use a 48-10F bent to 46 in place of 9-P. I’ve been “spoiled” with a 7 wood- 27H combo for well over 15 years. I’ve been using the 910F-816H1 setup since 2019.

Like most things, the real answer is, "it depends", If your 7 iron club head speed is 85, it seems like you're sort of on the cusp between "stock" R and "stock" S flex. So then onto your swing, and how you generate that speed. Is your transition quick? Is your turn deep? Are you on plane all the way? Do you like a particular shot shape or trajectory? All those elements factor in to which shaft you should be playing. Of course, the obvious answer, which others have pointed out is, see a fitter, but if you're determined to get the input of Team Titleist, without any other information, I guess that my answer is, "get what you think makes the most sense to you." Ultimately, with all the data points considered, it's really an either or choice. You will accommodate to whatever you decide so just pick one. Are you young? Getting stronger, getting faster, getting weaker, or slower? All those data points will point you in a direction. In the most global terms, if you struggle to hit it higher, get the softer shafts. If you want to keep it down with a more penetrating ball flight, get the firmer shafts.