Recently had the pleasure of picking up a USAF model of a tek 545. I know that most of the components found in these units were of higher quality, but given that this thing is approaching 70 years old, what should be replaced? My intentions were to replace the caps in both the LV and HV power supplies then go for a slow power up, monitoring voltages coming off of the power supply, fixing problems as they come along. How reliable are the rest of the capacitors for an occasional use setting? (Once a week or every other) Should all of the electrolytics and paper tubular caps be replaced? What about reforming for the electrolytics?

Tektronix used good components, often the best money could buy. I would definitely not "shotgun" the unit and replace everything. You could have some issues with power supply capacitors; you may not. I would attempt a slow power up monitoring the capacitors in the power supply. If they get warm, they are bad. I don't know if the 545 has tantalum capacitors. The are notorious for failure and fail short circuit.

I have a type 531 vacuum tube Tektronix scope (1954-1959) and it still has all of the original power supply capacitors... and it works!

The 545 and its Lavoie clone were made into the 1960s, so it may not be as old as you think. Did you get a manual with it?

Those scopes use a plug-in vertical module to configure it for different applications; the most popular was the CA dual-trace unit. Make sure that you have one, as the scope won't work without it.