Who would you consider to be the best, current, gunsmith for the Browning Lever Action?

Don't know of anyone. The only one I knew of in the past was Z Hat custom. Last I hear a whole lot of people are looking for him. So he is probable not a good option. Choose a smith carefully as the BLR is a real bitch to put back together right. I sent mine to Browning repair and it came back with the action out of time and would not fire.

Don't know if they can help you or not, but might check out Midwest Gun Works who is a supplier of Browning firearms, parts, etc. Out of curiosity, what 'smith work are you wanting done for your BLR??

I want a BLR in .450 Marlin rechambered to .458 WSM.

I worked at a shop that handled warranty work for Browning, and most everyone else, back in the '70's. Putting them back together can be a little "trying" the first time, but it's really not that bad, just a matter of timing. I eventually bought and use an '81 in .358. I like it - alot. The only work it's required is trigger work. Friend has an early Belgium-made model that was given him as a gift. Some years ago, he took it apart and lost the sear. We spent a year looking for parts - Midwest was no help, Browning was even less help. Finally bought all the internals on eBay on 2 different auctions. Think he paid $150 or so and was happy to do it. I picked up an extractor, just in case. If it wasn't for the lack of parts support, BLR's in .308 would replace the half dozen or so Marlin 336's we have scattered throughout the family. No trouble supporting them! Haven't looked at the specs for your rechambering but would sure check feeding through the magazine.