Estimate log space required for ALTER TABLE ALTER COLUMN

I need to change the width of a SQL Server 2008 R2 varchar column from 1000 to 60. Data is already < 60. The table is wide and has over 2 Billion rows with insufficient space on its data drives for the create another table - insert approaches. Recovery is simple. I executed ALTER TABLE ALTER COLUMN my column varchar(60) and I just enjoyed a 19 hour rollback after filling up the log drive. I am looking for a way to guesstimate log useage before shrinking other db log files, moving log files to other drives etc and trying again.

carpe cras