Any Hollowgram experts out there - spider question.

[rain dogs]

I think I'm overthinking this....

If I want to change the spider on my hollowgram cranks from 110mm bcd to a spider that can take a 44/30 for example, I need to use one of the mtn spiders, but they make so many different mountain spiders does it matter which I use? Or is that just dictated by the rings (which I'm yet to buy.)

68mm bottom bracket shell. No need to change the axle I assume? just smaller rings. I guess I'm wondering if the mtb spiders also have some weird offsets or geometry due to longer/different mtb spindles in addition to all those funky spacings and 4 hole mtb mountings and such. I know little to nothing about mtb standards.

?