Best kit of the Jolly Green & Super Jolly Green?

Academy did the three engined 53. A bigger bird and different tail configuration. The Revell kit is not bad and comes with everything you need except perhaps the armament. Which you can get from Cobra company

http://www.cobracompany.com/48049.htm

Any chance of converting one of the Academy later model CH-53s, or are there just too many differences?

Hallo, I recived today a conversion kit to have a CH-3E/HH3-E from a hasegawa/revell kit of sh 3d in 1/48, produced from attic aircraft this conversion is realy bad, full of babble and poor in detail, ...but it's the only one and at least it's a start point. 

In 1/48th there is not much to choose from for those birds. Revell has done a CH/HH-53 but it is not currently in production. It is still fairly common to find on ebay though, and they did do an Air Force Vietnam issue of the kit. For the CH/HH-3 there are no mainstream injection molded kits out there. One could take a 1/48 Hasegawa SH-3 and heavily modify it, but that is the only choice out here for now.