I've bought many components just to have on hand. It's needlessly frustrating to start a project and find I have to put it on hold for some 2 cent part. As a general rule, ceramic disc caps don't need replacing.
l would recommend you stick with electrolytics and paper caps if you just want to replace something carte blanche.
...and what I have are Sprague 1,000 vdc orange drops..
Depends on where they are used.
There is a chart about
half way down this page you may find useful, regarding the various capacitor types and the circuit they may be used in. Of course as in anything electronic, there are other factors to influence your final decision, but this gives a place to start.
If you want to replace the rectifiers, I'd put some series resistance in the string as well, if for no other reason than to reduce inrush current. I used
100 Ohm, 5 Watt wire wound resistors, to somewhat compensate for the original tube rectifiers internal voltage drop at the expected load. A quick look at the tube manual will give you what you need.