I put a Kato mechanism in an LL body quite successfully with a permanent 'glue up' of the LL body followed by some aggressive dremeling to get things out of the way. I did not have to narrow the mechanism, and there were no issues with truck clearances. Photos if you need them, but I've posted them over on Atlas and Trainboard before. The LL mech has its fans, but what finally pushed me over the edge was the better slow-speed electrical pickup of the Kato - really helps to have fully equalized trucks.