Thanks, but a little more info is still needed really. It'd be a good bet that you will need Dual Plys, but you didn't say if you are a smooth rider or not, whether you pick smooth lines, tend to jump rough sections or plow them, like your bike to change direction quickly and easily and sprint well out of corners or like it stable and both wheels in contact with the ground as much as possible. or for that matter whether you are a precise rider or a clueless chancer.
I'm a similar weight reasonably quick DHer and these days (no more racing)I can get away with a single ply front for DH anywhere that's not too rocky.
compound – again, you need to give more info on what you want from the tyre, a 60a rolls noticably faster than 42a/3C/40a. and grip is just fine if you aren't looking to be pushing for the absolute last bit of grip on every corner.
Size – again, what do you want? a narrower rear tyre will accelerate faster but will need more pressure not to pinch, a fatter front makes sense for most DH tracks but there are occasionally conditions where a 2.35 front makes sense even for a bigger rider.
Don't think you have said what has made you choose the Highroller in the first place either. to be perfectly honest I'd only ever run a highroller on the rear, for me, the way I ride a Minion DHF is way better than a high roller for control/predictability.
Seems like a sensible question to me 🙄
🙂