Might not be useful for tops, but here is some useful information on clouds in general that you can put in your back pocket:

Cloud Bases:
Temperature(F) minus dewpoint divided by 4.4, then multiplyed by 1000.
Temperature(C) minus dewpoint divided by 2.5, then multiplyed by 1000.
temp - DP X either 200 (if using C) or 400 (if using F)

If reading temps from a digital ATIS, use the T000000 series of numbers for the exact temp spread.... IE temp 6 C and Dewpoint 7 C in the ATIS can be found again at the end as T056074 meaning 5.6 degrees C temp and 7.4 degrees C on the DP... the difference being 1.8. 1.8 x 200 = 360 feet estimated bases... with just the ATIS 6/7 you'd come up with 200 for the bases and be significantly off....

yes, if you HAVE to be mr perfect, use the 4.4 and 2.2 OR 440 feet and 220 feet per degree.

USMCFLYR