I'm getting ready to order the parts for a fork, but I'm not sure how to calculate correct steerer length. Specifically, how much steerer goes inside the fork crown?

Here's my simple steerer length math:

Headtube Length = 180mm
Stack Height = 32mm (estimated, don't have headset yet, but it's 1" threaded)
Penetration into fork crown = ?? (about 1" or 25mm?)

So: 180 + 32 + ?? (25?) = 237mm

Another issue: Nova has a 240mm threaded steerer, but it's out of stock. Could I cut down a 270mm steerer? It's got a 50mm butt, so I'd lose about 33mm of it.


Thanks!