I spoke with Mark Penrod just yesterday on a pair of custom rifles I'm considering, both 7mm, one on the 84L, one on the 8400.
Mark said that Lilja has a stainless barrel that duplicates the 8400 (he wasn't able to recall the name of the barrel, it may have been actually been a contour made for another manufacturer that closely replicates Kimber's contour....)
He suggested contacting Lilja for the 84L.
IIRC, Mark did say that cutting the barrel channel is a nightmare, that the Kevlar would need to be layed up by hand which is a major PITA.
Long story short, a phone call to Lilja seems your best bet.
Hope this helps...