I would worry about added material to make a set. I'm sure it would not be an issue but I like the idea of a solid piece better.
I did some digging as the old Polaris Tipped up rail design was only 2.8 degrees that started 1/3 the rail length from the back of the rail. So if you use those numbers on a 174 you would end up with a tipped up rail starting at approx. 24" from the rear of the rail and it would raise the rail up .97"
I have access to the UHMW bar stock in 1-1/4" x 2" or 3" at 60" long in black (Stock overall Hyfax size is 1-1/4" wide x 7/8" tall). Those are not too expensive. I also already have a brand new set of hyfax for my 174 to take all of the notch dimensions from. I'm going to build a set just like your concept that has an extra 1" added to the front that tappers down to the stock thickness in the rear. I'm going to use this as a test along with the Skinz ARC system that I picked up dirt cheap to see if this actually gains any change in sled handling. I'm not expecting 155 playful out of this but a bit more than the current setup would be fun. I'm also going to see if I can find a router/mill bit that could cut the Polaris rail profile groove in one pass or two passes. That would make it much easier to test this as you could reproduce them quick.
Here is basically what would happen if you take the old Polaris Tipped up rail design and morph it into the 174 rail length for visual reference:
View attachment 402421