The coolant temperature and suction gages are pretty common. The fuel gage, if it is the right type for a P-40, is far less common. Keep looking on eBay. Try a saved search of the instruments you're looking for so it sends you an automatic email when they come up, but keep the search wording basic, such as "climb" or "gyro" or horizon". You might try Warbirdparts.com also. He has a selection of gages, but try not to faint at the prices.
This is a plan for a P-40E panel. I have a larger file of this plan at home and will be happy to send it to you if you get me an email address, but don't post it here, get it to me in a PM.