Wildfire,
My 450 Ackley was done (metalwork wise) by Alan Swan in Brisbane, he did all the action work to it originally.
Jim Kent did the new bolt handle however, and Jim did the whole lot of the 500 Jeffery.
Any good gunsmith should be able to get a 458 Lott to work for you, and also cut the action down.
The cock on opening kit is from Dayton Traister, both my rifle have Timney triggers as well.
A bit of work in an M17, but worth it.

Regards,
David.