The way to do this is to take the filtration numbers from the previous package, subtract your standard filtration and then add the new package's filtration. Here's an example. This will get you close enough that just one or two prints will nail down your new standard filtration settings for the next paper package. Naturally, you are not obliged to print the slide so that its colours are a clone of the original. Make than sunset yellower or that snow scene bluer.
Creativity is the soul of printing.
Printed on CLM1K medium contrast paper. In Ilfochrome printing time, temperature and agitation are critical. The motorised drum roller takes care of the latter, and good technique can take care of achieving consistent process timing. But, temperature control can be difficult to achieve without one of the more expensive automatic processors. There is a way though, and while it appears to have fallen into neglect for many years, Mr. Simon Ratowski, the inventor of the drum processor, developed it.