Easy there, fella. To the best of my knowledge, nobody posting here has an "ultimate accuracy" rifle, or is seriously involved in rim fire accuracy, either in competition or the building of such rifles. There are some such folk on RFC, which is arguably a much better source of rim fire information than here. People here, such as myself, can best be described as interested amateurs, no matter the depth of knowledge we might possess on certain topics.
Yes, there are some very good rifles in this circle, but you said "the most accurate possible", which significantly narrows down the options.
I can still help you along a little. First, let's take a look at what is currently the most accurate rim fire in the world: Calfee Spec 5 "Black Death"
Barrel: Shilen Rachet, 24"
Trigger: Modified FF
Action: E-Turbo
Chamber: Calfee spec, 2° leade, 0.155" engraving
Where is there to go from here? Look out for the new V-3 Turbo, triple lug action with crescent shaped firing pin. Barrels... a number of manufacturers make excellent blanks, the difference will be mainly in how well the Smith does their work. Top picks include Shilen rachet, Muller corrugated 8, MI-4, modified MI-4, and 90 driver.