https://www.jpinstruments.com/shop/edm-760/
Probably the least expense. If you buy at Sun N Fun or Oshkosh they offer a nice rebate. This will do fuel flow also and could be added later to spread out the love
I really like mine but I know there are other units out there that are good too. A lot of info for the buck with the Insight G4 too
http://www.insightavionics.com/bestg4t.htm
I have seen the G4 and it has a lot of different info in one package.
I installed my own EDM760 so cost was minimal. Not a huge project but time consuming running all the wires to the rear engine. Make sure they know it's a Skymaster when you order